Linux-PAM pam_userdb Observable Timing Discrepancy in Plaintext Password Comparison
Summary
| CVE | CVE-2026-54411 |
|---|---|
| State | PUBLISHED |
| Assigner | TuranSec |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-14 18:17:20 UTC |
| Updated | 2026-08-10 12:17:17 UTC |
| Description | 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. |
Risk And Classification
Primary CVSS: v4.0 6.9 MEDIUM from 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c
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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:N/R:X/V:D/RE:X/U:X
EPSS: 0.003330000 probability, percentile 0.258460000 (date 2026-08-10)
Problem Types: CWE-208 | CWE-208 CWE-208 Observable Timing Discrepancy
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | Secondary | 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/C... |
| 4.0 | CNA | CVSS | 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/A... |
| 3.1 | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | Secondary | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
| 3.1 | CNA | CVSS | 5.9 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N |
CVSS v4.0 Breakdown
Attack Vector
NetworkAttack Complexity
HighAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
NoneAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:N/R:X/V:D/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
NoneAvailability
NoneCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/linux-pam/linux-pam/blob/master/libpam/include/pam_inline.h | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | github.com | |
| cwe.mitre.org/data/definitions/208.html | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | cwe.mitre.org | |
| github.com/linux-pam/linux-pam | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | github.com | |
| github.com/linux-pam/linux-pam/blob/master/modules/pam_userdb/pam_userdb.c | 309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Xurshidbek Sobirjonov (en)
There are currently no legacy QID mappings associated with this CVE.