CyberSecBulletin
CVE-2025-23013NVD status: Deferred

pam-u2f: Unexpected Status Code or Return Value

Published Updated By the CyberSecBulletin desk

CVE-2025-23013 is a high-severity unexpected status code or return value vulnerability in pam-u2f from Yubico, with a CVSS 4.0 base score of 7.3 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists version 1.3.1 as the first without the flaw, so updating pam-u2f to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.4% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update pam-u2f to 1.3.1 or a later version.
  2. Read the advisory on yubico.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Yubicopam-u2fbefore 1.3.11.3.1

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
LocalThe attacker needs local access or must trick a user into running something.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Attack requirements
PresentThe target must be in a specific state or configuration for the attack to work.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Confidentiality (vulnerable system)
HighSerious loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
HighSerious loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
NoneNo loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
NoneNo loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
NoneNo loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/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:X/R:X/V:X/RE:X/U:X. Scored by CNA (mitre.org).

Official description

In Yubico pam-u2f before 1.3.1, local privilege escalation can sometimes occur. This product implements a Pluggable Authentication Module (PAM) that can be deployed to support authentication using a YubiKey or other FIDO compliant authenticators on macOS or Linux. This software package has an issue that allows for an authentication bypass in some configurations. An attacker would require the ability to access the system as an unprivileged user. Depending on the configuration, the attacker may also need to know the user's password.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Unexpected Status Code or Return Value

The product does not properly check when a function or operation returns a value that is legitimate for the function, but is not expected by the product.

More Unexpected Status Code or Return Value vulnerabilities (CWE-394)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

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