CVE-2026-48066: pam_usb: Thread-unsafe static pointer in log.c causes data race under concurrent PAM authentication
Vulnerability summary
CVE-2026-48066 is a medium (CVSS 5.7) Race Condition vulnerability in mcdope pam_usb. EPSS estimates a 0.14% chance of exploitation in the next 30 days, higher than 3.1% of scored vulnerabilities.
Timeline
- 27-05-2026PublishedVulnerability first disclosed.
- 28-05-2026Last modifiedVulnerability information updated.
Description
pam_usb provides hardware authentication for Linux using ordinary removable media. Prior to 0.9.1, src/log.c contains a process-wide static pointer that is written on every PAM invocation with the address of a stack-local variable. This violates the PAM re-entrancy requirement and creates a data race when the PAM stack is invoked concurrently from multiple threads. This vulnerability is fixed in 0.9.1.
CVSS metrics
2 scores · 2 sources · 1 version- NVDNIST5.7MediumCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
EPSS trend
Probability
0.14%
Chance of exploitation in the next 30 days
Percentile
3%
Versus all other CVEs
30-day change
Increase +0.03 pp
From 0.12% on 22-09-2026
Known exploited
Compare KEV catalogsNot in the CISA KEV catalog.
Not in the ENISA CNW catalog.
Not in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
- CWE-476NULL Pointer DereferenceThe product dereferences a pointer that it expects to be valid but is NULL.
Affected systems
Mcdope1 product
- pam_usb< 0.9.1
1 vendor · 1 product
References
3 links- github.com/mcdope/pam_usb/security/advisories/GHSA-qg76-57wq-mpv6X Refsource CONFIRM
- github.com/mcdope/pam_usb/issues/350X Refsource MISC
- github.com/mcdope/pam_usb/issues/55X Refsource MISC