Vulnerability-Lookup

PYSEC-2026-3682

Vulnerability from pysec - Published: 2026-08-19 11:56 - Updated: 2026-08-19 12:16

Details

Summary

Every Linuxfabrik check plugin that supports the shared --test argument (routed through lib.lftest.test()) will, when --test is supplied, treat the first CSV element as a filesystem path and read its full contents as the plugin's simulated STDOUT — running as root when the plugin is invoked through the shipped nagios/icinga sudoers allowlist. --test is a live production argument (centrally mapped to argparse.SUPPRESS, so it is hidden from --help but still accepted on the command line), not a build-time-only gate. This yields an arbitrary root file-read primitive (full disclosure on deb-updates; filtered disclosure / existence-and-readability oracle on ~22 other whitelisted plugins), i.e. local privilege escalation from the nagios account to root.

Root Cause

lib.lftest.test(args) (lftest.py lines 659-664): stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout). Element[1] (stderr channel) is read the same way. There is no path confinement on the supplied path.
check-plugins/deb-updates/deb-updates: --test is registered with type=lib.args.csv (lines 78-82). When supplied, control flows to stdout, _, retc = lib.lftest.test(args.TEST) (line 143), bypassing the apt path (if args.TEST is None: at 121). Each returned line is stored as a package row and, under the default --query='1' (WHERE 1, matches all rows), every row is printed via '\n* '.join([row['package'] ...]) → lib.base.oao(...).
The same --test/lib.lftest.test() mechanism exists identically on ~22 whitelisted plugins (e.g. docker-info), each performing a root open()/read of the attacker-named path. Disclosure degree varies by each plugin's downstream parser: full (deb-updates), filtered (docker-info echoes lines containing warning:/error:; openvpn-client-list echoes CLIENT_LIST lines), or existence/readability oracle (JSON parsers).

Impact

An attacker controlling the low-privilege nagios/icinga account (the documented threat model for the shipped sudoers file — same precondition as CVE-2026-52817) obtains the full contents of any root-readable file via deb-updates (e.g. /etc/shadow, /root/.ssh/id_*, TLS keys, cloud credentials), plus a fleet-wide root file existence/readability oracle and filtered content leak via the other plugins → local privilege escalation to root.

Proof of Concept

Full disclosure (deb-updates):

sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0

Filtered disclosure / oracle (docker-info, target routed to the stderr channel that gets echoed):

sudo /usr/lib64/nagios/plugins/docker-info --test="dummy,/etc/shadow,0"

Attack Chain

Entry: sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0
Action: the nagios user invokes the whitelisted plugin as root with a --test CSV whose element[0] is the target path and retc=0.
Guard: sudoers (Debian.sudoers:3) lists the binary only; --test is not gated to test builds.
Bypass proof: CONTRIBUTING.md documents --test as centrally mapped to argparse.SUPPRESS — hidden from --help but still accepted on the command line; lib.args.csv splits /etc/shadow,,0 into ['/etc/shadow','','0'].
Sink: lib.lftest.test(args.TEST) (deb-updates:143) reads element[0] as a file, as root.
Guard: none — no path confinement on element[0].
Bypass proof (from lib source): lftest.py:661-664: stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout) — element[0], if it exists on disk, is opened and its contents returned as stdout. retc=0 (element[2]) so there is no early cu() abort.
Store + query: each line → lib.db_sqlite.insert(conn, {'package': item}, ...); default QUERY='1' → SELECT * FROM deb_updates WHERE 1.
Guard: --only-critical or a restrictive --query would filter, but both default to permissive (ONLY_CRITICAL=False, QUERY='1').
Bypass proof: attacker passes neither → all rows selected.
Disclosure: msg += '\n* '.join([row['package'] for row in result]) → lib.base.oao(...) → stdout.
Guard: none.
Bypass proof: with len(result) > 0 the branch prints every row (every file line).
Impact: full contents of any root-readable file disclosed to the nagios user → root. On the ~22 other --test plugins the same primitive yields a filtered leak / universal root file existence-and-readability oracle.

Bypass Evidence

lib.lftest.test() file-read behavior verified directly from linuxfabrik-lib source (lftest.py:659-664, disk.read_file(stdout) when os.path.isfile(stdout)).
--test registration (type=lib.args.csv) and the stdout, _, retc = lib.lftest.test(args.TEST) call verified on the latest release tag v6.0.0 at check-plugins/deb-updates/deb-updates:143 (GitHub contents API); default QUERY='1' confirmed.
No path-confinement guard exists on the --test path element in either the plugin or lib.lftest.

Affected Versions

<= 6.0.0 (latest release; --test/lib.lftest.test() flow present on tag v6.0.0). Not covered by any existing advisory (none reference --test or arbitrary file read).

Suggested Fix

Compile --test out of production builds (or gate it behind an explicit build/dev flag so it is not accepted at runtime), OR confine the --test path element(s) to a dedicated fixtures directory via realpath() + containment check before disk.read_file(). As defense-in-depth, constrain the sudoers entries to specific argument values so --test cannot be supplied to a root-run plugin.

Reported by zx (Jace)

Severity

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Impacted products

Name	purl
linuxfabrik-lib	pkg:pypi/linuxfabrik-lib

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "linuxfabrik-lib",
        "purl": "pkg:pypi/linuxfabrik-lib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.0.0.0",
        "2.0.0.7",
        "2.1.0.0",
        "2.1.0.4",
        "2.1.1.15",
        "2.1.1.5",
        "2.1.1.7",
        "2.2.0",
        "2.2.1",
        "2.3.0",
        "2.4.0",
        "3.0.0",
        "3.1.0",
        "3.1.1",
        "3.2.0",
        "3.3.0",
        "3.4.0",
        "3.4.1",
        "4.0.0",
        "4.0.1",
        "4.0.2",
        "4.1.0",
        "4.2.0",
        "4.3.0",
        "4.4.0",
        "5.0.0",
        "5.1.0",
        "6.0.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-73974",
    "GHSA-rh9c-rqvg-f7pr"
  ],
  "details": "## Summary\nEvery Linuxfabrik check plugin that supports the shared `--test` argument (routed through `lib.lftest.test()`) will, when `--test` is supplied, treat the first CSV element as a filesystem path and read its full contents as the plugin\u0027s simulated STDOUT \u2014 running as root when the plugin is invoked through the shipped `nagios`/`icinga` sudoers allowlist. `--test` is a **live production argument** (centrally mapped to `argparse.SUPPRESS`, so it is hidden from `--help` but still accepted on the command line), not a build-time-only gate. This yields an arbitrary root file-read primitive (full disclosure on `deb-updates`; filtered disclosure / existence-and-readability oracle on ~22 other whitelisted plugins), i.e. local privilege escalation from the `nagios` account to root.\n\n## Root Cause\n- `lib.lftest.test(args)` (`lftest.py` lines 659-664): `stdout = args[0]`; `if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout)`. Element[1] (stderr channel) is read the same way. There is **no path confinement** on the supplied path.\n- `check-plugins/deb-updates/deb-updates`: `--test` is registered with `type=lib.args.csv` (lines 78-82). When supplied, control flows to `stdout, _, retc = lib.lftest.test(args.TEST)` (line 143), bypassing the apt path (`if args.TEST is None:` at 121). Each returned line is stored as a `package` row and, under the default `--query=\u00271\u0027` (`WHERE 1`, matches all rows), every row is printed via `\u0027\\n* \u0027.join([row[\u0027package\u0027] ...])` \u2192 `lib.base.oao(...)`.\n- The same `--test`/`lib.lftest.test()` mechanism exists identically on ~22 whitelisted plugins (e.g. `docker-info`), each performing a root `open()`/read of the attacker-named path. Disclosure degree varies by each plugin\u0027s downstream parser: full (`deb-updates`), filtered (`docker-info` echoes lines containing `warning:`/`error:`; `openvpn-client-list` echoes `CLIENT_LIST` lines), or existence/readability oracle (JSON parsers).\n\n## Impact\nAn attacker controlling the low-privilege `nagios`/`icinga` account (the documented threat model for the shipped sudoers file \u2014 same precondition as CVE-2026-52817) obtains the full contents of any root-readable file via `deb-updates` (e.g. `/etc/shadow`, `/root/.ssh/id_*`, TLS keys, cloud credentials), plus a fleet-wide root file existence/readability oracle and filtered content leak via the other plugins \u2192 local privilege escalation to root.\n\n## Proof of Concept\nFull disclosure (deb-updates):\n```\nsudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0\n```\nFiltered disclosure / oracle (docker-info, target routed to the stderr channel that gets echoed):\n```\nsudo /usr/lib64/nagios/plugins/docker-info --test=\"dummy,/etc/shadow,0\"\n```\n\n## Attack Chain\n1. **Entry:** `sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0`\n   - **Action:** the nagios user invokes the whitelisted plugin as root with a `--test` CSV whose element[0] is the target path and retc=0.\n   - **Guard:** sudoers (Debian.sudoers:3) lists the binary only; `--test` is not gated to test builds.\n   - **Bypass proof:** CONTRIBUTING.md documents `--test` as centrally mapped to `argparse.SUPPRESS` \u2014 hidden from `--help` but still accepted on the command line; `lib.args.csv` splits `/etc/shadow,,0` into `[\u0027/etc/shadow\u0027,\u0027\u0027,\u00270\u0027]`.\n2. **Sink:** `lib.lftest.test(args.TEST)` (deb-updates:143) reads element[0] as a file, as root.\n   - **Guard:** none \u2014 no path confinement on element[0].\n   - **Bypass proof (from lib source):** `lftest.py:661-664`: `stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout)` \u2014 element[0], if it exists on disk, is opened and its contents returned as stdout. `retc=0` (element[2]) so there is no early `cu()` abort.\n3. **Store + query:** each line \u2192 `lib.db_sqlite.insert(conn, {\u0027package\u0027: item}, ...)`; default `QUERY=\u00271\u0027` \u2192 `SELECT * FROM deb_updates WHERE 1`.\n   - **Guard:** `--only-critical` or a restrictive `--query` would filter, but both default to permissive (`ONLY_CRITICAL=False`, `QUERY=\u00271\u0027`).\n   - **Bypass proof:** attacker passes neither \u2192 all rows selected.\n4. **Disclosure:** `msg += \u0027\\n* \u0027.join([row[\u0027package\u0027] for row in result])` \u2192 `lib.base.oao(...)` \u2192 stdout.\n   - **Guard:** none.\n   - **Bypass proof:** with `len(result) \u003e 0` the branch prints every row (every file line).\n5. **Impact:** full contents of any root-readable file disclosed to the nagios user \u2192 root. On the ~22 other `--test` plugins the same primitive yields a filtered leak / universal root file existence-and-readability oracle.\n\n## Bypass Evidence\n- `lib.lftest.test()` file-read behavior verified directly from linuxfabrik-lib source (`lftest.py:659-664`, `disk.read_file(stdout)` when `os.path.isfile(stdout)`).\n- `--test` registration (`type=lib.args.csv`) and the `stdout, _, retc = lib.lftest.test(args.TEST)` call verified on the latest release tag **v6.0.0** at `check-plugins/deb-updates/deb-updates:143` (GitHub contents API); default `QUERY=\u00271\u0027` confirmed.\n- No path-confinement guard exists on the `--test` path element in either the plugin or `lib.lftest`.\n\n## Affected Versions\n`\u003c= 6.0.0` (latest release; `--test`/`lib.lftest.test()` flow present on tag v6.0.0). Not covered by any existing advisory (none reference `--test` or arbitrary file read).\n\n## Suggested Fix\nCompile `--test` out of production builds (or gate it behind an explicit build/dev flag so it is not accepted at runtime), OR confine the `--test` path element(s) to a dedicated fixtures directory via `realpath()` + containment check before `disk.read_file()`. As defense-in-depth, constrain the sudoers entries to specific argument values so `--test` cannot be supplied to a root-run plugin.\n\n---\nReported by **zx (Jace)**",
  "id": "PYSEC-2026-3682",
  "modified": "2026-08-19T12:16:28.037522Z",
  "published": "2026-08-19T11:56:28.745844Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/commit/d665042c55fae83a295ebc0023e8b77f6c473a28"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/releases/tag/v6.1.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/linuxfabrik-lib"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-rh9c-rqvg-f7pr"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-73974"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)"
}

CVE-2026-73974 (GCVE-0-2026-73974)

Vulnerability from cvelistv5 – Published: 2026-08-18 21:15 – Updated: 2026-08-19 17:09

Title

linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)

Summary

linuxfabrik-lib provides Python modules for database access, caching, shell execution, and API integrations, and Linuxfabrik Monitoring Plugins uses its shared testing helper across check plugins. Prior to linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0, lib.lftest.test() treated the first or second element of a --test CSV argument as a filesystem path and returned the file contents as simulated standard output or standard error without path confinement. The hidden but production-accessible --test argument was accepted by sudo-authorized plugins, so an attacker controlling the nagios or icinga account could use check-plugins/deb-updates/deb-updates with its default QUERY=1 to disclose every line of a root-readable file. Approximately 22 other plugins exposed filtered content or a root file existence and readability oracle through the same helper, while check-plugins/network-bonding/network-bonding and check-plugins/openstack-swift-stat/openstack-swift-stat had direct read paths that bypassed the helper. The library fix confines fixture reads to the invoking plugin's unit-test directory and refuses unsafe anchors, and the plugin fix routes the two bypasses through that helper. These issues are fixed in linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0.

Severity

5.5 (Medium)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-19 16:55 UTC

CWE

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-269 - Improper Privilege Management

Assigner

GitHub_M mitre root

References

5 references

URL	Tags
https://github.com/Linuxfabrik/monitoring-plugins…	x_refsource_CONFIRM
https://github.com/Linuxfabrik/lib/commit/d665042…	x_refsource_MISC
https://github.com/Linuxfabrik/monitoring-plugins…	x_refsource_MISC
https://github.com/Linuxfabrik/lib/releases/tag/v6.1.0	x_refsource_MISC
https://github.com/Linuxfabrik/monitoring-plugins…	x_refsource_MISC

Impacted products

2 products

Vendor	Product	Version
Linuxfabrik	monitoring-plugins	Affected: < 7.0.0
Linuxfabrik	lib	Affected: < 6.0.1

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-73974",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-19T16:55:07.626828Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-19T17:09:41.147Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "monitoring-plugins",
          "vendor": "Linuxfabrik",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 7.0.0"
            }
          ]
        },
        {
          "product": "lib",
          "vendor": "Linuxfabrik",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 6.0.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "linuxfabrik-lib provides Python modules for database access, caching, shell execution, and API integrations, and Linuxfabrik Monitoring Plugins uses its shared testing helper across check plugins. Prior to linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0, lib.lftest.test() treated the first or second element of a --test CSV argument as a filesystem path and returned the file contents as simulated standard output or standard error without path confinement. The hidden but production-accessible --test argument was accepted by sudo-authorized plugins, so an attacker controlling the nagios or icinga account could use check-plugins/deb-updates/deb-updates with its default QUERY=1 to disclose every line of a root-readable file. Approximately 22 other plugins exposed filtered content or a root file existence and readability oracle through the same helper, while check-plugins/network-bonding/network-bonding and check-plugins/openstack-swift-stat/openstack-swift-stat had direct read paths that bypassed the helper. The library fix confines fixture reads to the invoking plugin\u0027s unit-test directory and refuses unsafe anchors, and the plugin fix routes the two bypasses through that helper. These issues are fixed in linuxfabrik-lib 6.1.0 and Linuxfabrik Monitoring Plugins 7.0.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "LOCAL",
            "availabilityImpact": "NONE",
            "baseScore": 5.5,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-22",
              "description": "CWE-22: Improper Limitation of a Pathname to a Restricted Directory (\u0027Path Traversal\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-269",
              "description": "CWE-269: Improper Privilege Management",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-18T21:15:03.324Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr"
        },
        {
          "name": "https://github.com/Linuxfabrik/lib/commit/d665042c55fae83a295ebc0023e8b77f6c473a28",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Linuxfabrik/lib/commit/d665042c55fae83a295ebc0023e8b77f6c473a28"
        },
        {
          "name": "https://github.com/Linuxfabrik/monitoring-plugins/commit/f6680a9e4b39569f318feefdb2f51e5d18c7dad5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Linuxfabrik/monitoring-plugins/commit/f6680a9e4b39569f318feefdb2f51e5d18c7dad5"
        },
        {
          "name": "https://github.com/Linuxfabrik/lib/releases/tag/v6.1.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Linuxfabrik/lib/releases/tag/v6.1.0"
        },
        {
          "name": "https://github.com/Linuxfabrik/monitoring-plugins/releases/tag/v7.0.0",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/Linuxfabrik/monitoring-plugins/releases/tag/v7.0.0"
        }
      ],
      "source": {
        "advisory": "GHSA-rh9c-rqvg-f7pr",
        "discovery": "UNKNOWN"
      },
      "title": "linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73974",
    "datePublished": "2026-08-18T21:15:03.324Z",
    "dateReserved": "2026-08-13T21:42:04.044Z",
    "dateUpdated": "2026-08-19T17:09:41.147Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-RH9C-RQVG-F7PR

Vulnerability from github – Published: 2026-08-18 21:18 – Updated: 2026-08-18 21:18

Summary

linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)

Details

Summary

Root Cause

lib.lftest.test(args) (lftest.py lines 659-664): stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout). Element[1] (stderr channel) is read the same way. There is no path confinement on the supplied path.
check-plugins/deb-updates/deb-updates: --test is registered with type=lib.args.csv (lines 78-82). When supplied, control flows to stdout, _, retc = lib.lftest.test(args.TEST) (line 143), bypassing the apt path (if args.TEST is None: at 121). Each returned line is stored as a package row and, under the default --query='1' (WHERE 1, matches all rows), every row is printed via '\n* '.join([row['package'] ...]) → lib.base.oao(...).
The same --test/lib.lftest.test() mechanism exists identically on ~22 whitelisted plugins (e.g. docker-info), each performing a root open()/read of the attacker-named path. Disclosure degree varies by each plugin's downstream parser: full (deb-updates), filtered (docker-info echoes lines containing warning:/error:; openvpn-client-list echoes CLIENT_LIST lines), or existence/readability oracle (JSON parsers).

Impact

Proof of Concept

Full disclosure (deb-updates):

sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0

Filtered disclosure / oracle (docker-info, target routed to the stderr channel that gets echoed):

sudo /usr/lib64/nagios/plugins/docker-info --test="dummy,/etc/shadow,0"

Attack Chain

Entry: sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0
Action: the nagios user invokes the whitelisted plugin as root with a --test CSV whose element[0] is the target path and retc=0.
Guard: sudoers (Debian.sudoers:3) lists the binary only; --test is not gated to test builds.
Bypass proof: CONTRIBUTING.md documents --test as centrally mapped to argparse.SUPPRESS — hidden from --help but still accepted on the command line; lib.args.csv splits /etc/shadow,,0 into ['/etc/shadow','','0'].
Sink: lib.lftest.test(args.TEST) (deb-updates:143) reads element[0] as a file, as root.
Guard: none — no path confinement on element[0].
Bypass proof (from lib source): lftest.py:661-664: stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout) — element[0], if it exists on disk, is opened and its contents returned as stdout. retc=0 (element[2]) so there is no early cu() abort.
Store + query: each line → lib.db_sqlite.insert(conn, {'package': item}, ...); default QUERY='1' → SELECT * FROM deb_updates WHERE 1.
Guard: --only-critical or a restrictive --query would filter, but both default to permissive (ONLY_CRITICAL=False, QUERY='1').
Bypass proof: attacker passes neither → all rows selected.
Disclosure: msg += '\n* '.join([row['package'] for row in result]) → lib.base.oao(...) → stdout.
Guard: none.
Bypass proof: with len(result) > 0 the branch prints every row (every file line).
Impact: full contents of any root-readable file disclosed to the nagios user → root. On the ~22 other --test plugins the same primitive yields a filtered leak / universal root file existence-and-readability oracle.

Bypass Evidence

lib.lftest.test() file-read behavior verified directly from linuxfabrik-lib source (lftest.py:659-664, disk.read_file(stdout) when os.path.isfile(stdout)).
--test registration (type=lib.args.csv) and the stdout, _, retc = lib.lftest.test(args.TEST) call verified on the latest release tag v6.0.0 at check-plugins/deb-updates/deb-updates:143 (GitHub contents API); default QUERY='1' confirmed.
No path-confinement guard exists on the --test path element in either the plugin or lib.lftest.

Affected Versions

<= 6.0.0 (latest release; --test/lib.lftest.test() flow present on tag v6.0.0). Not covered by any existing advisory (none reference --test or arbitrary file read).

Suggested Fix

Reported by zx (Jace)

Severity

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "linuxfabrik-lib"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-73974"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22",
      "CWE-269"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-18T21:18:59Z",
    "nvd_published_at": null,
    "severity": "MODERATE"
  },
  "details": "## Summary\nEvery Linuxfabrik check plugin that supports the shared `--test` argument (routed through `lib.lftest.test()`) will, when `--test` is supplied, treat the first CSV element as a filesystem path and read its full contents as the plugin\u0027s simulated STDOUT \u2014 running as root when the plugin is invoked through the shipped `nagios`/`icinga` sudoers allowlist. `--test` is a **live production argument** (centrally mapped to `argparse.SUPPRESS`, so it is hidden from `--help` but still accepted on the command line), not a build-time-only gate. This yields an arbitrary root file-read primitive (full disclosure on `deb-updates`; filtered disclosure / existence-and-readability oracle on ~22 other whitelisted plugins), i.e. local privilege escalation from the `nagios` account to root.\n\n## Root Cause\n- `lib.lftest.test(args)` (`lftest.py` lines 659-664): `stdout = args[0]`; `if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout)`. Element[1] (stderr channel) is read the same way. There is **no path confinement** on the supplied path.\n- `check-plugins/deb-updates/deb-updates`: `--test` is registered with `type=lib.args.csv` (lines 78-82). When supplied, control flows to `stdout, _, retc = lib.lftest.test(args.TEST)` (line 143), bypassing the apt path (`if args.TEST is None:` at 121). Each returned line is stored as a `package` row and, under the default `--query=\u00271\u0027` (`WHERE 1`, matches all rows), every row is printed via `\u0027\\n* \u0027.join([row[\u0027package\u0027] ...])` \u2192 `lib.base.oao(...)`.\n- The same `--test`/`lib.lftest.test()` mechanism exists identically on ~22 whitelisted plugins (e.g. `docker-info`), each performing a root `open()`/read of the attacker-named path. Disclosure degree varies by each plugin\u0027s downstream parser: full (`deb-updates`), filtered (`docker-info` echoes lines containing `warning:`/`error:`; `openvpn-client-list` echoes `CLIENT_LIST` lines), or existence/readability oracle (JSON parsers).\n\n## Impact\nAn attacker controlling the low-privilege `nagios`/`icinga` account (the documented threat model for the shipped sudoers file \u2014 same precondition as CVE-2026-52817) obtains the full contents of any root-readable file via `deb-updates` (e.g. `/etc/shadow`, `/root/.ssh/id_*`, TLS keys, cloud credentials), plus a fleet-wide root file existence/readability oracle and filtered content leak via the other plugins \u2192 local privilege escalation to root.\n\n## Proof of Concept\nFull disclosure (deb-updates):\n```\nsudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0\n```\nFiltered disclosure / oracle (docker-info, target routed to the stderr channel that gets echoed):\n```\nsudo /usr/lib64/nagios/plugins/docker-info --test=\"dummy,/etc/shadow,0\"\n```\n\n## Attack Chain\n1. **Entry:** `sudo /usr/lib64/nagios/plugins/deb-updates --test=/etc/shadow,,0`\n   - **Action:** the nagios user invokes the whitelisted plugin as root with a `--test` CSV whose element[0] is the target path and retc=0.\n   - **Guard:** sudoers (Debian.sudoers:3) lists the binary only; `--test` is not gated to test builds.\n   - **Bypass proof:** CONTRIBUTING.md documents `--test` as centrally mapped to `argparse.SUPPRESS` \u2014 hidden from `--help` but still accepted on the command line; `lib.args.csv` splits `/etc/shadow,,0` into `[\u0027/etc/shadow\u0027,\u0027\u0027,\u00270\u0027]`.\n2. **Sink:** `lib.lftest.test(args.TEST)` (deb-updates:143) reads element[0] as a file, as root.\n   - **Guard:** none \u2014 no path confinement on element[0].\n   - **Bypass proof (from lib source):** `lftest.py:661-664`: `stdout = args[0]; if stdout and os.path.isfile(stdout): _, stdout = disk.read_file(stdout)` \u2014 element[0], if it exists on disk, is opened and its contents returned as stdout. `retc=0` (element[2]) so there is no early `cu()` abort.\n3. **Store + query:** each line \u2192 `lib.db_sqlite.insert(conn, {\u0027package\u0027: item}, ...)`; default `QUERY=\u00271\u0027` \u2192 `SELECT * FROM deb_updates WHERE 1`.\n   - **Guard:** `--only-critical` or a restrictive `--query` would filter, but both default to permissive (`ONLY_CRITICAL=False`, `QUERY=\u00271\u0027`).\n   - **Bypass proof:** attacker passes neither \u2192 all rows selected.\n4. **Disclosure:** `msg += \u0027\\n* \u0027.join([row[\u0027package\u0027] for row in result])` \u2192 `lib.base.oao(...)` \u2192 stdout.\n   - **Guard:** none.\n   - **Bypass proof:** with `len(result) \u003e 0` the branch prints every row (every file line).\n5. **Impact:** full contents of any root-readable file disclosed to the nagios user \u2192 root. On the ~22 other `--test` plugins the same primitive yields a filtered leak / universal root file existence-and-readability oracle.\n\n## Bypass Evidence\n- `lib.lftest.test()` file-read behavior verified directly from linuxfabrik-lib source (`lftest.py:659-664`, `disk.read_file(stdout)` when `os.path.isfile(stdout)`).\n- `--test` registration (`type=lib.args.csv`) and the `stdout, _, retc = lib.lftest.test(args.TEST)` call verified on the latest release tag **v6.0.0** at `check-plugins/deb-updates/deb-updates:143` (GitHub contents API); default `QUERY=\u00271\u0027` confirmed.\n- No path-confinement guard exists on the `--test` path element in either the plugin or `lib.lftest`.\n\n## Affected Versions\n`\u003c= 6.0.0` (latest release; `--test`/`lib.lftest.test()` flow present on tag v6.0.0). Not covered by any existing advisory (none reference `--test` or arbitrary file read).\n\n## Suggested Fix\nCompile `--test` out of production builds (or gate it behind an explicit build/dev flag so it is not accepted at runtime), OR confine the `--test` path element(s) to a dedicated fixtures directory via `realpath()` + containment check before `disk.read_file()`. As defense-in-depth, constrain the sudoers entries to specific argument values so `--test` cannot be supplied to a root-run plugin.\n\n---\nReported by **zx (Jace)**",
  "id": "GHSA-rh9c-rqvg-f7pr",
  "modified": "2026-08-18T21:18:59Z",
  "published": "2026-08-18T21:18:59Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins/security/advisories/GHSA-rh9c-rqvg-f7pr"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/commit/d665042c55fae83a295ebc0023e8b77f6c473a28"
    },
    {
      "type": "WEB",
      "url": "https://github.com/Linuxfabrik/lib/releases/tag/v6.1.0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/Linuxfabrik/monitoring-plugins"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "linuxfabrik-lib: Arbitrary root file read via live --test argument (lib.lftest) across sudoers-whitelisted plugins (LPE)"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

PYSEC-2026-3682

Summary

Root Cause

Impact

Proof of Concept

Attack Chain

Bypass Evidence

Affected Versions

Suggested Fix

CVE-2026-73974 (GCVE-0-2026-73974)

GHSA-RH9C-RQVG-F7PR

Summary

Root Cause

Impact

Proof of Concept

Attack Chain

Bypass Evidence

Affected Versions

Suggested Fix

Tags

Sightings

Nomenclature

Related by attack behaviour