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CVE-2026-126831VulnerabilityPublished Updated

write_out_tar_header() with long usernames/groupnames · Cpio: cpio: stack-based buffer overflow

Affects MicrosoftSource GCVE Database

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Authoritative record:CVE-2026-126831· Medium 5.5

Not known to be exploited · CVSS 5.5 Medium.

Data as of 15 Nov 2026, 10:24 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (redhat)CVSS 3.15.5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 14 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Red Hat Enterprise Linux 10cpioAffected–Fixed in–
Red Hat Enterprise Linux 6cpioAffected–Fixed in–
Red Hat Enterprise Linux 7cpioAffected–Fixed in–
Red Hat Enterprise Linux 8cpioAffected–Fixed in–
Red Hat Enterprise Linux 9cpioAffected–Fixed in–
Red Hat Hardened ImagescpioAffected–Fixed in–

AI-suggested

Users should monitor Microsoft Security Response Center advisories for updates.

Description

A stack-based buffer overflow vulnerability exists in the cpio utility's write_out_tar_header() function when processing long usernames or groupnames. This flaw affects specific versions of the Microsoft product identified as versions 3.0 and 4.0. No CVSS score or detailed impact information is provided, and no known exploits are reported in the wild.

References

Community reviews

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