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CVE-2026-126831

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

  • Medium 5.5

Description

A flaw was found in cpio. A local user can cause a Denial of Service (DoS) by triggering a stack-based buffer overflow when creating archives in tar or ustar formats. When archiving files owned by users or groups with names exceeding 32 characters, cpio copies these names into fixed-size memory without verifying their length. This unbounded copy corrupts stack memory and causes the application to crash.

Key facts

Published
12 Nov 2026
Last changed
13 Nov 2026
Assigned by
redhat
EPSS
0.105% likely to be exploited in the next 30 days, higher than 1.102% of CVEs (scores for 15 Nov 2026)
SSVC (CISA)
Exploitation: none; Automatable: no; Technical impact: partial

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

  • 5.5CVSS 3.1, Mediumfrom the CNA (redhat)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

VendorProductVersions
Red HatRed Hat Enterprise Linux 10
  • Default status: affected
Red HatRed Hat Enterprise Linux 6
  • Default status: affected
Red HatRed Hat Enterprise Linux 7
  • Default status: affected
Red HatRed Hat Enterprise Linux 8
  • Default status: affected
Red HatRed Hat Enterprise Linux 9
  • Default status: affected
Red HatRed Hat Hardened Images
  • Default status: affected

Timeline

  1. 7 Nov 2026 Made public.
  2. 11 Nov 2026 Reported to Red Hat.
  3. 12 Nov 2026 Published

Weakness

References