pam_usb: xfree() does not call explicit_bzero — sensitive cryptographic material may linger in freed heap

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Summary

CVECVE-2026-48984
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-18 18:16:19 UTC
Updated2026-06-18 20:16:14 UTC
Descriptionpam_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).

Risk And Classification

Primary CVSS: v3.1 4.7 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Problem Types: CWE-14 | CWE-226 | CWE-14 CWE-14: Compiler Removal of Code to Clear Buffers | CWE-226 CWE-226: Sensitive Information in Resource Not Removed Before Reuse

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
3.1CNADECLARED4.7MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mcdope Pam Usb affected < 0.9.2 Not specified

References

ReferenceSourceLinkTags
github.com/mcdope/pam_usb/releases/tag/0.9.2 [email protected] github.com
github.com/mcdope/pam_usb/security/advisories/GHSA-rmp6-wfrq-wrrc [email protected] github.com
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