Vulnerability-Lookup

OESA-2026-2902 (CVE-2026-54411)

Vulnerability from osv_openeuler – Published: 2026-07-09 11:11 – Updated: 2026-08-06 11:11 – Source website

Summary

pam security update

Details

PAM (Pluggable Authentication Modules) is a system of libraries that handle the authentication tasks of applications (services) on the system.

Security Fix(es):

Linux-PAM through 1.7.2 contains an observable timing discrepancy (CWE-208) in the pam_userdb module's plaintext-password comparison path in modules/pam_userdb/pam_userdb.c that allows a local or network-adjacent attacker able to repeatedly drive authentication through a calling service to recover the plaintext password of a target account by measuring response-timing differences. The comparison uses strncmp() (or strncasecmp() when PAM_ICASE_ARG is set) preceded by a length-equality check, so the time to reject a candidate depends on the index of the first differing byte and on whether the candidate's length matches the stored password, leaking the password length and individual prefix bytes. The vulnerable path is reached when the administrator configures pam_userdb with crypt=none, with an unrecognized crypt method, or without a crypt= argument, causing the module to store and compare credentials in plaintext.(CVE-2026-54411)

Severity

6.9 (Medium)


                    
                      CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/AU:N/V:D

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-54411	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "pam-1.5.3-12.oe2403sp1.aarch64.rpm",
          "pam-debuginfo-1.5.3-12.oe2403sp1.aarch64.rpm",
          "pam-debugsource-1.5.3-12.oe2403sp1.aarch64.rpm",
          "pam-devel-1.5.3-12.oe2403sp1.aarch64.rpm"
        ],
        "noarch": [
          "pam-help-1.5.3-12.oe2403sp1.noarch.rpm"
        ],
        "src": [
          "pam-1.5.3-12.oe2403sp1.src.rpm"
        ],
        "x86_64": [
          "pam-1.5.3-12.oe2403sp1.x86_64.rpm",
          "pam-debuginfo-1.5.3-12.oe2403sp1.x86_64.rpm",
          "pam-debugsource-1.5.3-12.oe2403sp1.x86_64.rpm",
          "pam-devel-1.5.3-12.oe2403sp1.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "pam",
        "purl": "pkg:rpm/openEuler/pam\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.5.3-12.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Medium"
  },
  "details": "PAM (Pluggable Authentication Modules) is a system of libraries that handle the authentication tasks of applications (services) on the system.\r\n\r\nSecurity Fix(es):\n\nLinux-PAM through 1.7.2 contains an observable timing discrepancy (CWE-208) in the pam_userdb module\u0026apos;s plaintext-password comparison path in modules/pam_userdb/pam_userdb.c that allows a local or network-adjacent attacker able to repeatedly drive authentication through a calling service to recover the plaintext password of a target account by measuring response-timing differences. The comparison uses strncmp() (or strncasecmp() when PAM_ICASE_ARG is set) preceded by a length-equality check, so the time to reject a candidate depends on the index of the first differing byte and on whether the candidate\u0026apos;s length matches the stored password, leaking the password length and individual prefix bytes. The vulnerable path is reached when the administrator configures pam_userdb with crypt=none, with an unrecognized crypt method, or without a crypt= argument, causing the module to store and compare credentials in plaintext.(CVE-2026-54411)",
  "id": "OESA-2026-2902",
  "modified": "2026-08-06T11:11:48Z",
  "published": "2026-07-09T11:11:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2902"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54411"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/AU:N/V:D",
      "type": "CVSS_V4"
    }
  ],
  "summary": "pam security update",
  "upstream": [
    "CVE-2026-54411"
  ]
}

CVE-2026-54411 (GCVE-0-2026-54411)

Vulnerability from cvelistv5 – Published: 2026-06-14 17:21 – Updated: 2026-08-10 11:43

Title

Linux-PAM pam_userdb Observable Timing Discrepancy in Plaintext Password Comparison

Summary

Severity

6.9 (Medium)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/AU:N/V:D

5.9 (Medium)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-15 16:59 UTC

CWE

CWE-208 - Observable Timing Discrepancy

Assigner

TuranSec redhat root

References

4 references

URL	Tags
https://github.com/linux-pam/linux-pam	product
https://github.com/linux-pam/linux-pam/blob/maste…	product
https://github.com/linux-pam/linux-pam/blob/maste…	product
https://cwe.mitre.org/data/definitions/208.html	technical-description

Impacted products

1 product

Vendor	Product	Version
Linux-PAM	Linux-PAM	Affected: 0 , ≤ 1.7.2 (semver)

Date Public

2026-06-14 17:21

Credits

Xurshidbek Sobirjonov

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54411",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-15T16:59:25.401303Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-15T16:59:37.818Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://github.com/linux-pam/linux-pam",
          "defaultStatus": "unknown",
          "modules": [
            "pam_userdb"
          ],
          "product": "Linux-PAM",
          "programFiles": [
            "modules/pam_userdb/pam_userdb.c"
          ],
          "repo": "https://github.com/linux-pam/linux-pam",
          "vendor": "Linux-PAM",
          "versions": [
            {
              "lessThanOrEqual": "1.7.2",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Xurshidbek Sobirjonov"
        }
      ],
      "datePublic": "2026-06-14T17:21:43.853Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eLinux-PAM through 1.7.2 contains an observable timing discrepancy (CWE-208) in the pam_userdb module\u0027s plaintext-password comparison path in modules/pam_userdb/pam_userdb.c that allows a local or network-adjacent attacker able to repeatedly drive authentication through a calling service to recover the plaintext password of a target account by measuring response-timing differences.\u003c/p\u003e"
            }
          ],
          "value": "Linux-PAM through 1.7.2 contains an observable timing discrepancy (CWE-208) in the pam_userdb module\u0027s plaintext-password comparison path in modules/pam_userdb/pam_userdb.c that allows a local or network-adjacent attacker able to repeatedly drive authentication through a calling service to recover the plaintext password of a target account by measuring response-timing differences."
        }
      ],
      "impacts": [
        {
          "descriptions": [
            {
              "lang": "en",
              "value": "An attacker who can repeatedly drive authentication through a service that invokes pam_userdb with plaintext-password configuration and without an artificial failure delay can measure response-timing differences to learn the correct password length and recover the plaintext password byte by byte. Recovery requires many measurements per character and is sensitive to scheduling and network jitter; recovery of one user\u0027s secret does not by itself yield access to other accounts. Practical exploitation is gated by an administrative misconfiguration (pam_userdb storing passwords in plaintext, reached when the module is configured with crypt=none, with an unknown crypt method, or with no crypt= option) and by the absence of failure-delay or rate-limiting in the calling service."
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NO",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.9,
            "baseSeverity": "MEDIUM",
            "exploitMaturity": "PROOF_OF_CONCEPT",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "DIFFUSE",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/AU:N/V:D",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "NONE",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "An attacker repeatedly authenticates through a service that calls pam_userdb (plaintext mode) and measures the time the service takes to reject each candidate password to learn the password length and recover the password one byte at a time."
            }
          ]
        },
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.9,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-208",
              "description": "CWE-208 Observable Timing Discrepancy",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-10T11:43:56.355Z",
        "orgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
        "shortName": "TuranSec"
      },
      "references": [
        {
          "name": "Linux-PAM - upstream repository",
          "tags": [
            "product"
          ],
          "url": "https://github.com/linux-pam/linux-pam"
        },
        {
          "name": "Vulnerable plaintext-password comparison in pam_userdb.c (master)",
          "tags": [
            "product"
          ],
          "url": "https://github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c#L327"
        },
        {
          "name": "pam_consttime_streq helper available for the remediation",
          "tags": [
            "product"
          ],
          "url": "https://github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h"
        },
        {
          "name": "CWE-208: Observable Timing Discrepancy",
          "tags": [
            "technical-description"
          ],
          "url": "https://cwe.mitre.org/data/definitions/208.html"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Linux-PAM pam_userdb Observable Timing Discrepancy in Plaintext Password Comparison",
      "x_assigner_notes": "The vulnerable comparison was verified by direct source inspection of modules/pam_userdb/pam_userdb.c at tag v1.7.2 and at master HEAD as of disclosure: lines 327-332 perform a length-equality early exit followed by strncmp() / strncasecmp(). Linux-PAM has previously addressed the same weakness class in a sibling module: NEWS for Release 1.7.0 records \"pam_unix: compare password hashes in constant time\", and Release 1.6.0 hardened pam_mkhomedir \"against timing attacks\". The pam_consttime_streq() helper used by those fixes lives in libpam/include/pam_inline.h, which pam_userdb.c already includes, so the remediation in pam_userdb is a drop-in replacement of the strncmp call. The v1.7.2 release notes do not list a pam_userdb hardening change. Exploitation is gated by (a) the administrator having configured pam_userdb with plaintext password storage (crypt=none, unknown crypt method, or no crypt= option), a discouraged but documented configuration; and (b) the calling service not applying an authentication-failure delay - both gates raise attack complexity and bound real-world impact, so CVSS is scored MEDIUM rather than HIGH consistent with prior CWE-208 timing-leak CVE scoring.",
      "x_author": "Xurshidbek Sobirjonov"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
    "assignerShortName": "TuranSec",
    "cveId": "CVE-2026-54411",
    "datePublished": "2026-06-14T17:21:43.853Z",
    "dateReserved": "2026-06-13T16:39:46.122Z",
    "dateUpdated": "2026-08-10T11:43:56.355Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

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