CVE-2026-48984 pam_usb: xfree() does not call explicit_bzero — sensitive cryptographic material may linger in freed heap
Failure to zero memory before freeing in pam_usb may allow recovery of sensitive authentication material from heap memory.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-48984?
CVE-2026-48984 is a medium-severity vulnerability in mcdope pam_usb, published on 18 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
pam_usb provides hardware authentication for Linux using ordinary removable media. In versions 0.9.1 and below, the xfree() memory release helper in calls free() without first zeroing the buffer contents, releasing heap-allocated buffers containing sensitive data — including one-time pad bytes read from disk — without clearing, leaving the sensitive content in freed heap memory until it happens to be overwritten by a subsequent allocation. On a system where a use-after-free condition exists, or where a heap inspection primitive becomes available, this could allow recovery of pad values or other authentication material from freed memory regions. This is a defence-in-depth requirement consistent with prior hardening work in this codebase (GHSA-vx6f-rrqr-j87c applied explicit_bzero to some pad paths; this issue generalises the pattern to the central deallocation helper).
Which versions are affected by CVE-2026-48984?
How do I fix CVE-2026-48984?
No fix has been published for CVE-2026-48984 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-48984 being exploited?
There is no known exploitation of CVE-2026-48984 in the wild and no public exploit code.
Sources
Also known as GHSA-rmp6-wfrq-wrrc.