CVE-2026-48984: CWE-14: Compiler Removal of Code to Clear Buffers in mcdope pam_usb
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).
AI Analysis
Technical Summary
The vulnerability in pam_usb (versions 0.9.1 and earlier) arises because the xfree() memory release helper calls free() on heap-allocated buffers without zeroing their contents beforehand. These buffers contain sensitive data including one-time pad bytes used for authentication. Without clearing, sensitive data remains in freed memory until overwritten, potentially exposing it if a use-after-free or heap inspection is possible. This generalizes a prior hardening pattern that applied explicit zeroing to some pad paths, extending it to the central deallocation helper.
Potential Impact
Sensitive authentication material such as one-time pad bytes may remain in freed heap memory, potentially allowing an attacker with the ability to exploit use-after-free conditions or perform heap memory inspection to recover these secrets. This could compromise hardware authentication security on affected Linux systems using pam_usb. The confidentiality of authentication data is impacted, but integrity and availability are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are currently provided. Until a patch is available, users should be aware of the risk of sensitive data exposure due to improper memory clearing. Monitor vendor communications for updates on remediation.
CVE-2026-48984: CWE-14: Compiler Removal of Code to Clear Buffers in mcdope pam_usb
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).
CVSS v3.1
Score 4.7medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in pam_usb (versions 0.9.1 and earlier) arises because the xfree() memory release helper calls free() on heap-allocated buffers without zeroing their contents beforehand. These buffers contain sensitive data including one-time pad bytes used for authentication. Without clearing, sensitive data remains in freed memory until overwritten, potentially exposing it if a use-after-free or heap inspection is possible. This generalizes a prior hardening pattern that applied explicit zeroing to some pad paths, extending it to the central deallocation helper.
Potential Impact
Sensitive authentication material such as one-time pad bytes may remain in freed heap memory, potentially allowing an attacker with the ability to exploit use-after-free conditions or perform heap memory inspection to recover these secrets. This could compromise hardware authentication security on affected Linux systems using pam_usb. The confidentiality of authentication data is impacted, but integrity and availability are not affected.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are currently provided. Until a patch is available, users should be aware of the risk of sensitive data exposure due to improper memory clearing. Monitor vendor communications for updates on remediation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-26T23:26:07.975Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a343000f198dc38c138471d
Added to database: 6/18/2026, 5:50:56 PM
Last enriched: 6/18/2026, 6:05:19 PM
Last updated: 6/18/2026, 11:50:37 PM
Views: 8
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