CVE-2026-64667: Out-of-bounds Read (CVSS 4.4)

Description

pam_usb provides hardware authentication for Linux using removable media. Prior to version 0.9.3, src/local.c (pusb_get_tty_from_display_server) allocates a 4096-byte cmdline buffer, reads up to 4096 bytes from /proc//cmdline, then replaces every NUL separator with a space. When read(2) returns exactly 4096 bytes for any process the function inspects, the buffer ends without a terminator and the subsequent strstr() calls scan past the allocation boundary. The function is invoked during normal PAM authentication when DISPLAY is set, so the read fires for every process at auth time. Consequences are bounded: strstr output is a Boolean substring match (limited info-disclosure surface) but a hostile heap layout can produce a SIGSEGV that terminates the host PAM process. This issue has been patched in version 0.9.3.

Is your site exposed to CVE-2026-64667?

Run a free security scan — no signup, results in seconds.

CVSS v3.1 Score

4.4

MEDIUM

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

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-125 Out-of-bounds Read

References

Other References

https://github.com/mcdope/pam_usb/commit/d0a2e716241304cdb069adfaf54d2ede629d57fa https://github.com/mcdope/pam_usb/issues/411 https://github.com/mcdope/pam_usb/pull/426 https://github.com/mcdope/pam_usb/releases/tag/0.9.3 https://github.com/mcdope/pam_usb/security/advisories/GHSA-gc6f-5hpq-ghxh

Frequently Asked Questions

What is CVE-2026-64667? +

pam_usb provides hardware authentication for Linux using removable media. Prior to version 0.9.3, src/local.c (pusb_get_tty_from_display_server) allocates a 4096-byte cmdline buffer, reads up to 4096 bytes from /proc//cmdline, then replaces every NUL separator with a space. When read(2) returns exactly 4096 bytes for any process the function inspects, the buffer ends without a terminator and the subsequent strstr() calls scan past the allocation boundary. The function is invoked during normal PAM authentication when DISPLAY is set, so the read fires for every process at auth time. Consequences are bounded: strstr output is a Boolean substring match (limited info-disclosure surface) but a hostile heap layout can produce a SIGSEGV that terminates the host PAM process. This issue has been patched in version 0.9.3. It has a CVSS v3.1 base score of 4.4 (MEDIUM).

How severe is CVE-2026-64667? +

CVE-2026-64667 has a CVSS v3.1 score of 4.4 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-64667? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-29013

libcoap contains out-of-bounds read vulnerabilities in OSCORE Appendix B.2 CBOR unwrap handling where get_byte_inc() in src/oscore/oscore_cbor.c relies solely on assert() …

CVE-2026-53566

Out-of-bounds read vulnerability in Citrix Citrix Secure Access Client for Windows. This issue affects Citrix Secure Access Client for Windows: …

CVE-2026-3508

An Out-of-bounds Read vulnerability in the IOCTL handler in ASUS System Control Interface allows a local user to cause system …

CVE-2025-48520

An improper input validation vulnerability within the AMD Platform Management Framework (PMF) driver can allow a local attacker to read …

CVE-2026-3894

Out-of-bounds Read vulnerability in RTI Connext Professional (Core Libraries) allows Overread Buffers.This issue affects Connext Professional: from 7.4.0 before 7.7.0, …

CVE-2025-4098

Horner Automation Cscape version 10.0 (10.0.415.2) SP1 is vulnerable to an out-of-bounds read vulnerability that could allow an attacker to …