CVE-2026-126831
Cpio: cpio: stack-based buffer overflow in write_out_tar_header() with long usernames/groupnames
CVE-2026-126831 is a medium vulnerability (CVSS 5.5) in Red Hat Enterprise Linux 10, published November 12, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.10%, the 1st percentile. No source names a fixed version.
- Severity
- 5.5 MediumCVSS 3.1, CVE List
- Exploit chance
- 0.10%EPSS, 1st percentile
- Exploitation
- None knownNot on CISA’s or ENISA’s lists
- Fixed in
- No fix listedNo source names one
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.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
cpioUbuntu:Pro:14.04:LTS | All versions, plus listed versions 2.11+dfsg-1ubuntu12.11+dfsg-1ubuntu1.12.11+dfsg-1ubuntu1.22.11+dfsg-1ubuntu1.2+esm12.11+dfsg-1ubuntu1.2+esm22.11+dfsg-1ubuntu1.2+esm3 | None known |
cpioUbuntu:Pro:16.04:LTS | All versions, plus listed versions 2.11+dfsg-4.1ubuntu12.11+dfsg-5ubuntu12.11+dfsg-5ubuntu1.12.11+dfsg-5ubuntu1.1+esm12.11+dfsg-5ubuntu1.1+esm2 | None known |
cpioUbuntu:Pro:18.04:LTS | All versions, plus listed versions 2.11+dfsg-62.12+dfsg-62.12+dfsg-6ubuntu0.18.04.12.12+dfsg-6ubuntu0.18.04.42.12+dfsg-6ubuntu0.18.04.4+esm1 | None known |
cpioUbuntu:Pro:20.04:LTS | All versions, plus listed versions 2.12+dfsg-92.12+dfsg-9ubuntu12.13+dfsg-12.13+dfsg-22.13+dfsg-2ubuntu0.32.13+dfsg-2ubuntu0.42.13+dfsg-2ubuntu0.4+esm1 | None known |
cpioUbuntu:22.04:LTS | All versions, plus listed versions 2.13+dfsg-4ubuntu42.13+dfsg-72.13+dfsg-7ubuntu0.12.13+dfsg-7ubuntu0.2 | None known |
cpioUbuntu:24.04:LTS | All versions, plus listed versions 2.13+dfsg-7.12.14+dfsg-12.15+dfsg-12.15+dfsg-1ubuntu12.15+dfsg-1ubuntu22.15+dfsg-1ubuntu2.1 | None known |
cpioUbuntu:26.10 | All versions, plus listed versions 2.15+dfsg-2.12.15+dfsg-2.1ubuntu1 | None known |
cpioUbuntu:26.04:LTS | All versions, plus listed versions 2.15+dfsg-2ubuntu12.15+dfsg-2.12.15+dfsg-2.1ubuntu0.1 | None known |
What each source reports
CVE List Score used
Cpio: cpio: stack-based buffer overflow in write_out_tar_header() with long usernames/groupnames
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.
- Record
CVE-2026-126831- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-121
- Updated
- 2026-11-12
EUVDEUVD-2026-124565
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.
- Record
EUVD-2026-124565- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-12
GitHub AdvisoriesGHSA-ffxh-f67m-r64f
A flaw was found in cpio. A local user can cause a Denial of Service (DoS) by triggering a stack...
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.
- Record
GHSA-ffxh-f67m-r64f- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-121
- Updated
- 2026-11-12
NVD
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.
- Record
CVE-2026-126831- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-121
- Updated
- 2026-11-13
OSVUBUNTU-CVE-2026-126831
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.
- Record
UBUNTU-CVE-2026-126831- CVSS 3.1
- 5.5 Medium
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-13
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | NVD, OSV | |
| published | EUVD | |
| published | EUVD | |
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.