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Vulnerability record · CVE-2025-71263 · published 13 March 2026

CVE-2025-71263: Opengroup unix classic buffer overflow vulnerability

Opengroup · Unix

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.

7.8 CVSS 3.1 High EPSS 0.18% · top 93.3% CWE-120 · Classic buffer overflow
7.8CVSS 3.1 base score
0.18%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

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/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://discuss.systems/@ricci/115747843169814700 Issue 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.html Issue TrackingMailing List
http://www.openwall.com/lists/oss-security/2026/03/20/6 Issue TrackingMailing List
http://www.openwall.com/lists/oss-security/2026/03/21/4 Issue TrackingMailing List

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2025-71263), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.