Vulnerability-Lookup

RHSA-2026:35016

Vulnerability from csaf_redhat - Published: 2026-07-02 18:21 - Updated: 2026-09-08 11:17

Summary

Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update

Severity

Moderate

Notes

Topic: An update for Red Hat Hardened Images RPMs is now available.

Details: This update includes the following RPMs: pam: * pam-1.7.2-2.2.hum1 (aarch64, x86_64) * pam-devel-1.7.2-2.2.hum1 (aarch64, x86_64) * pam-doc-1.7.2-2.2.hum1 (noarch) * pam-libs-1.7.2-2.2.hum1 (aarch64, x86_64) * pam-1.7.2-2.2.hum1.src (src) Security Fix(es): pam: * CVE-2026-54411

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-54411

A flaw was found in Linux-PAM's `pam_userdb` module. This vulnerability, categorized as an Observable Timing Discrepancy (CWE-208), allows a local or network-adjacent attacker to recover plaintext passwords. By repeatedly attempting authentication and measuring response-timing differences during plaintext password comparison, an attacker can deduce the password. This flaw is exploitable when the `pam_userdb` module is configured to store and compare credentials in plaintext, which is not a default setting.

4.8 (Medium)


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

CWE-208 - Observable Timing Discrepancy

Affected products

Fixed 4 products

Product	Version	Remediation
Unresolved product id: Red Hat Hardened Images:pam-main@aarch64	—	Vendor Fix fix Workaround
Unresolved product id: Red Hat Hardened Images:pam-main@noarch	—	Vendor Fix fix Workaround
Unresolved product id: Red Hat Hardened Images:pam-main@src	—	Vendor Fix fix Workaround
Unresolved product id: Red Hat Hardened Images:pam-main@x86_64	—	Vendor Fix fix Workaround

Threats

Impact Moderate

References

13 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:35016	self
https://access.redhat.com/security/cve/CVE-2026-54411	external
https://access.redhat.com/security/updates/classi…	external
https://images.redhat.com/	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-54411	self
https://bugzilla.redhat.com/show_bug.cgi?id=2488766	external
https://www.cve.org/CVERecord?id=CVE-2026-54411	external
https://nvd.nist.gov/vuln/detail/CVE-2026-54411	external
https://cwe.mitre.org/data/definitions/208.html	external
https://github.com/linux-pam/linux-pam	external
https://github.com/linux-pam/linux-pam/blob/maste…	external
https://github.com/linux-pam/linux-pam/blob/maste…	external

JSON

To clipboard

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      "cwe": {
        "id": "CWE-208",
        "name": "Observable Timing Discrepancy"
      },
      "discovery_date": "2026-06-14T18:00:55.002567+00:00",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "2488766"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "A flaw was found in Linux-PAM\u0027s `pam_userdb` module. This vulnerability, categorized as an Observable Timing Discrepancy (CWE-208), allows a local or network-adjacent attacker to recover plaintext passwords. By repeatedly attempting authentication and measuring response-timing differences during plaintext password comparison, an attacker can deduce the password. This flaw is exploitable when the `pam_userdb` module is configured to store and compare credentials in plaintext, which is not a default setting.",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "linux-pam: Plaintext password recovery via timing discrepancy in pam_userdb module",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "This Moderate flaw in Linux-PAM\u0027s `pam_userdb` module allows a local or network-adjacent attacker to recover plaintext passwords through a timing discrepancy. This vulnerability requires the `pam_userdb` module to be explicitly configured to store and compare credentials in plaintext, which is not a default or recommended configuration in Red Hat Enterprise Linux environments. The impact is limited by the need for repeated authentication attempts and specific, non-default module configurations.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
        "fixed": [
          "Red Hat Hardened Images:pam-main@aarch64",
          "Red Hat Hardened Images:pam-main@noarch",
          "Red Hat Hardened Images:pam-main@src",
          "Red Hat Hardened Images:pam-main@x86_64"
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        {
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          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2488766"
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        },
        {
          "category": "external",
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          "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-54411"
        },
        {
          "category": "external",
          "summary": "https://cwe.mitre.org/data/definitions/208.html",
          "url": "https://cwe.mitre.org/data/definitions/208.html"
        },
        {
          "category": "external",
          "summary": "https://github.com/linux-pam/linux-pam",
          "url": "https://github.com/linux-pam/linux-pam"
        },
        {
          "category": "external",
          "summary": "https://github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h",
          "url": "https://github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h"
        },
        {
          "category": "external",
          "summary": "https://github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c#L327",
          "url": "https://github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c#L327"
        }
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      "release_date": "2026-06-14T17:21:43.853000+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-07-02T18:21:37+00:00",
          "details": "For details on how to apply this update, which includes the changes described in this advisory, refer to:\nhttps://images.redhat.com/",
          "product_ids": [
            "Red Hat Hardened Images:pam-main@aarch64",
            "Red Hat Hardened Images:pam-main@noarch",
            "Red Hat Hardened Images:pam-main@src",
            "Red Hat Hardened Images:pam-main@x86_64"
          ],
          "restart_required": {
            "category": "none"
          },
          "url": "https://access.redhat.com/errata/RHSA-2026:35016"
        },
        {
          "category": "workaround",
          "details": "To mitigate this issue, administrators should ensure that the `pam_userdb` module is not configured to store or compare credentials in plaintext. Verify that `pam_userdb` is either configured with a strong cryptographic hashing method or, if not required, is disabled. Avoid using `crypt=none` or omitting the `crypt=` argument when configuring `pam_userdb`. If changes are made to PAM configuration files, services relying on PAM may need to be restarted for the changes to take effect.",
          "product_ids": [
            "Red Hat Hardened Images:pam-main@aarch64",
            "Red Hat Hardened Images:pam-main@noarch",
            "Red Hat Hardened Images:pam-main@src",
            "Red Hat Hardened Images:pam-main@x86_64"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          },
          "products": [
            "Red Hat Hardened Images:pam-main@aarch64",
            "Red Hat Hardened Images:pam-main@noarch",
            "Red Hat Hardened Images:pam-main@src",
            "Red Hat Hardened Images:pam-main@x86_64"
          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Moderate"
        }
      ],
      "title": "linux-pam: Plaintext password recovery via timing discrepancy in pam_userdb module"
    }
  ]
}

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

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.

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

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            }
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            {
              "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.

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.