CVE-2025-71263
In UNIX Fourth Research Edition (v4), the su command is vulnerable to a buffer overflow due to the 'password' variable having a fixed size of 100 bytes.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.18%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
In UNIX Fourth Research Edition (v4), the su command is vulnerable to a buffer overflow due to the 'password' variable having a fixed size of 100 bytes. A local user can exploit this to gain root privileges. It is unlikely that UNIX v4 is running anywhere outside of a very small number of lab environments. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
- CVSS 3.1
- 7.8 HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 0.18% probability · 8th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-120
- Affected
- opengroup/unix
- Source
- cve@mitre.org
References
- https://discuss.systems/@ricci/115747843169814700Issue Tracking
- https://sigma-star.at/blog/2025/12/unix-v4-buffer-overflow/Press/Media Coverage
- https://www.spinellis.gr/blog/20251223/Technical Description
- https://www.tuhs.org/pipermail/tuhs/2026-January/032991.htmlIssue Tracking, Mailing List
- http://www.openwall.com/lists/oss-security/2026/03/20/6Issue Tracking, Mailing List
- http://www.openwall.com/lists/oss-security/2026/03/21/4Issue Tracking, Mailing List
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.