{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-54411",
        "assignerOrgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
        "state": "PUBLISHED",
        "assignerShortName": "TuranSec",
        "dateReserved": "2026-06-13T16:39:46.122Z",
        "datePublished": "2026-06-14T17:21:43.853Z",
        "dateUpdated": "2026-08-10T11:43:56.355Z"
    },
    "containers": {
        "cna": {
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-208",
                            "description": "CWE-208 Observable Timing Discrepancy",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "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's 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."
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "Linux-PAM",
                    "product": "Linux-PAM",
                    "collectionURL": "https://github.com/linux-pam/linux-pam",
                    "repo": "https://github.com/linux-pam/linux-pam",
                    "modules": [
                        "pam_userdb"
                    ],
                    "programFiles": [
                        "modules/pam_userdb/pam_userdb.c"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "0",
                            "lessThanOrEqual": "1.7.2",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unknown"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "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.",
                    "supportingMedia": [
                        {
                            "type": "text/html",
                            "base64": false,
                            "value": "<p>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.</p>"
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/linux-pam/linux-pam",
                    "name": "Linux-PAM - upstream repository",
                    "tags": [
                        "product"
                    ]
                },
                {
                    "url": "https://github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c#L327",
                    "name": "Vulnerable plaintext-password comparison in pam_userdb.c (master)",
                    "tags": [
                        "product"
                    ]
                },
                {
                    "url": "https://github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h",
                    "name": "pam_consttime_streq helper available for the remediation",
                    "tags": [
                        "product"
                    ]
                },
                {
                    "url": "https://cwe.mitre.org/data/definitions/208.html",
                    "name": "CWE-208: Observable Timing Discrepancy",
                    "tags": [
                        "technical-description"
                    ]
                }
            ],
            "metrics": [
                {
                    "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."
                        }
                    ],
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "HIGH",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "exploitMaturity": "PROOF_OF_CONCEPT",
                        "Safety": "NOT_DEFINED",
                        "Automatable": "NO",
                        "Recovery": "NOT_DEFINED",
                        "valueDensity": "DIFFUSE",
                        "vulnerabilityResponseEffort": "NOT_DEFINED",
                        "providerUrgency": "NOT_DEFINED",
                        "version": "4.0",
                        "baseSeverity": "MEDIUM",
                        "baseScore": 6.9,
                        "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"
                    }
                },
                {
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV3_1": {
                        "version": "3.1",
                        "attackVector": "NETWORK",
                        "attackComplexity": "HIGH",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "scope": "UNCHANGED",
                        "confidentialityImpact": "HIGH",
                        "integrityImpact": "NONE",
                        "availabilityImpact": "NONE",
                        "baseSeverity": "MEDIUM",
                        "baseScore": 5.9,
                        "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N"
                    }
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Xurshidbek Sobirjonov",
                    "type": "finder"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "x_author": "Xurshidbek Sobirjonov",
            "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.",
            "title": "Linux-PAM pam_userdb Observable Timing Discrepancy in Plaintext Password Comparison",
            "providerMetadata": {
                "orgId": "309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c",
                "shortName": "TuranSec",
                "dateUpdated": "2026-08-10T11:43:56.355Z"
            },
            "datePublic": "2026-06-14T17:21:43.853Z"
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-06-15T16:59:25.401303Z",
                                "id": "CVE-2026-54411",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
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                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
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                "title": "CISA ADP Vulnrichment",
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                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-06-15T16:59:37.818Z"
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}