VulnerabilityPublished 11 Nov 2026

CVE-2026-64667: mcdope pam_usb · Out-of-bounds Read

Affects mcdope pam_usbSource CVE Database V5

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Not known to be exploited · CVSS 4.4 Medium : upgrade to 0.9.3 when convenient.

Data as of 11 Nov 2026, 04:05 UTC

CVSS 3.1 base score

4.4Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	4.4

Patch: Available – fixed in 0.9.3

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

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

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade mcdope pam_usb to 0.9.3.

Affected software

Product	Affected	Fixed in
mcdopepam_usb	Affected <0.9.3	Fixed in 0.9.3

AI-suggested

Upgrade pam_usb to version 0.9.3 or later, where this vulnerability is fixed. No other mitigation is required as the patch fully addresses the issue.

Description

CVE-2026-64667 is an out-of-bounds read vulnerability in pam_usb versions prior to 0.9.3. The flaw occurs in the function pusb_get_tty_from_display_server, which reads the /proc/<pid>/cmdline file into a fixed-size buffer without ensuring a null terminator when exactly 4096 bytes are read. This can cause subsequent string operations to read beyond the buffer boundary. The vulnerability is triggered during PAM authentication when the DISPLAY environment variable is set. The impact is limited to potential information disclosure and a possible crash (SIGSEGV) of the PAM process. The issue is fixed in pam_usb version 0.9.3.

Impact

The vulnerability can lead to limited information disclosure due to out-of-bounds reads and may cause the PAM process to crash with a segmentation fault (SIGSEGV) if a hostile heap layout is present. This could disrupt authentication services but does not allow privilege escalation or code execution. The CVSS score of 4.4 reflects a medium severity with local attack vector and low impact on confidentiality and availability.

Summary

The pam_usb module for Linux hardware authentication has a CWE-125 out-of-bounds read vulnerability in versions before 0.9.3. The vulnerable function allocates a 4096-byte buffer and reads up to 4096 bytes from the /proc/<pid>/cmdline file but does not append a null terminator if the read returns exactly 4096 bytes. Subsequent calls to strstr() scan past the buffer boundary, potentially causing a segmentation fault or limited information disclosure. This function is invoked during normal PAM authentication when the DISPLAY variable is set, making the vulnerability exploitable during authentication attempts. The issue has been patched in version 0.9.3.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 04:05 UTC

WeaknessesCWE-125

Technical details

References

Community reviews

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