PamHandle::get_user can cause an authentication bypass

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

No dated EPSS signal available.

As published by the source; long descriptions are shortened.

In affected versions, `PamHandle::get_user` can return `Err(PAM_SUCCESS)` after it gets the username successfully. PAM modules that return this "error" code from `sm_authenticate` or `sm_acct_mgmt` early-return a success code to PAM without doing any further verification. This means a user could log in when they shouldn't be able to (e.g., if the module is `sufficient`). The `pam_try!` macro of this crate early-returns the code in this exact way: ```rust fn sm_authenticate(pamh: &mut PamHandle, args: Vec , flags: PamFlag) -> PamResultCode { let user = pam_try!(pamh.get_user(None)); // Can return PAM_SUCCESS here. // If it does, the module does not get to this line. } ``` The root cause is an [incorrect FFI declaration][ffi-decl] for [`pam_get_user(3)`][pam-get-user]. This C function writes a pointer to the username through its `user` argument (of type `const char **user`). This crate's binding declared this argument as a shared reference (`&*mut c_char`). Writing through a shared…

Published by the source

2 Jun 2025, 12:00 UTC

Last modified by the source

26 Oct 2026, 14:00 UTC

Source last checked

27 Oct 2026, 06:25 UTC

1. Revision 1 · created · 27 Oct 2026

   Published from osv record RUSTSEC-2025-0173

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# Patch Next advisory brief: rustsec-2025-0173

Advisory: `PamHandle::get_user` can cause an authentication bypass
IDs: rustsec-2025-0173
Record: https://patchnext.com/advisories/rustsec-2025-0173 (revision 1, source checked 27 Oct 2026, 06:25 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pam-bindings 0.1.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io pam-bindings: affected >= 0.0.0-0, < 0.1.2; fixed in 0.1.2

## Suggested inspection (read-only)
- crates.io pam-bindings: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pam-bindings.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/RUSTSEC-2025-0173 (OSV record RUSTSEC-2025-0173 lists affected ranges: crates.io pam-bindings >=0.0.0-0 <0.1.2 (fixed))

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