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.
CVE-2025-71263
This high-severity CVE scores 7.8 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 92% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.8
- EG Score
- 7.8(medium)
- EG Risk
- 40(Track)EG Risk 40/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity78% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 8%
- KEV
- Not listed
Published
March 13, 2026
Last Modified
June 17, 2026
Advisory Details (6)
Auto-updated Jun 11, 2026oss-security - Re: Buffer overflow in /bin/su from UNIX v4
http://www.openwall.com/lists/oss-security/2026/03/21/4oss-security - Re: Buffer overflow in /bin/su from UNIX v4
http://www.openwall.com/lists/oss-security/2026/03/20/6[TUHS] Buffer overflow found/fixed in v4 tape ;)
https://www.tuhs.org/pipermail/tuhs/2026-January/032991.htmlblog dds: 2025-12-23 — An initial analysis of the discovered Unix V4 tape
https://www.spinellis.gr/blog/20251223/Fixing a Buffer Overflow in UNIX v4 Like It's 1973
https://sigma-star.at/blog/2025/12/unix-v4-buffer-overflow/Rob Ricci: "The attempt to read the UNIX V4 tape is underway!" - discuss.systems
https://discuss.systems/@ricci/115747843169814700Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 11× in last 7d / 45× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-27 14:13 UTCEPSS rescore
- 2026-07-26 14:54 UTCEPSS rescore
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- 2026-07-25 14:17 UTCEPSS rescore
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- 2026-07-23 14:18 UTCEPSS rescore
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- 2026-07-23 03:03 UTCEG score recompute▲ 0.40
- 2026-07-22 14:08 UTCEPSS rescore
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- 2026-07-19 14:30 UTCEPSS rescore
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- 2026-07-12 05:46 UTCEPSS rescore
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- 2026-06-28 04:56 UTCEPSS rescore
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- 2026-06-27 03:08 UTCEPSS rescore
- 2026-06-25 13:49 UTCEPSS rescore
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- 2026-06-24 14:05 UTCEPSS rescore
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- 2026-06-23 21:32 UTCEPSS rescore
- 2026-06-22 14:25 UTCEPSS rescore
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- 2026-06-21 14:56 UTCEPSS rescore
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- 2026-06-21 01:59 UTCEPSS rescore
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- 2026-06-19 19:25 UTCEPSS rescore
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- 2026-06-18 17:52 UTCEPSS rescore
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- 2026-06-17 17:53 UTCEPSS rescore
- 2026-06-16 17:52 UTCEPSS rescore
- 2026-06-15 17:48 UTCEPSS rescore
- 2026-06-14 23:18 UTCEPSS rescore
- 2026-06-13 23:00 UTCEPSS rescore
- 2026-06-13 23:00 UTCEPSS rescore
- 2026-06-12 23:12 UTCEPSS rescore
- 2026-06-12 23:12 UTCEPSS rescore
- 2026-06-11 21:57 UTCEG score recompute
- 2026-06-11 21:57 UTCGHSA enrichment
- 2026-06-11 21:57 UTCNVD updatefirst tracked
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Same CWE
10 shownCWE-120
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- CVE-2011-4862EG 10.0EPSS p100HIGH
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- CVE-2007-1770EG 10.0EPSS p97HIGH
- CVE-2002-1337EG 10.0EPSS p99HIGH
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Frequently asked(5)
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Dependency Blast Radius
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