CVSS 3.1
5.5 mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HCVE-2026-126831 Cpio: cpio: stack-based buffer overflow in write_out_tar_header() with long usernames/groupnames
Medium (5.5) in red hat. EPSS 0.1% estimated probability of exploitation activity in the next 30 days.
On this page
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.
Severity
- EPSS
- 0.1% estimated probability of exploitation activity in the next 30 days; 1st percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: no · Technical impact: partial, assessed 2026-11-13. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-121 Stack-based Buffer Overflow
- Published
- Modified
- Assigned by
- redhat (CNA)
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Affected
- red hat:red hat enterprise linux 10
- red hat:red hat enterprise linux 6
- red hat:red hat enterprise linux 7
- red hat:red hat enterprise linux 8
- red hat:red hat enterprise linux 9
- red hat:red hat hardened images
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Ubuntu | 22.04:LTS, 24.04:LTS, 26.04:LTS and 5 more | cpio | no fix listed | UBUNTU-CVE-2026-126831 |
From the distributions' data via OSV.dev: Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Ubuntu.
Red Hat
Red Hat rates this Moderate.
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | cpio | Affected | |
| Red Hat Enterprise Linux 6 | cpio | Affected | |
| Red Hat Enterprise Linux 7 | cpio | Affected | |
| Red Hat Enterprise Linux 8 | cpio | Affected | |
| Red Hat Enterprise Linux 9 | cpio | Affected | |
| Red Hat Hardened Images | cpio | Affected |
Contains Red Hat Security Data © Red Hat, Inc., licensed under CC BY 4.0. Source: https://access.redhat.com/security/data. Modified: reformatted. Red Hat's page for CVE-2026-126831.