CVE-2025-71263: In UNIX Fourth Research Edition (v4), the su command is vulnerable to a buffer overflow due to the 'password'

Routine

HIGH 7.4MITIGATE

CVE-2025-71263 is a high-severity flaw (CVSS 7.4) affecting unix. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.4 (High)
Attack vector	Local
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 92%)
CISA exploited list	No
Weakness	CWE-120
Published	2026-03-13
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: opengroup

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-13 19:53 UTCPublished CVE record published
2026-06-17 10:03 UTCUpdated Record last modified

opengroup unix MITIGATE

Affected: 4

Fixed in: no fixed release known

Safe to downgrade to: a release before 4

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-71263?

unix: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-71263 being exploited?

CVE-2025-71263 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-71263 affect?

CVE-2025-71263 affects unix. Severity is high (CVSS 7.4). 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 r

How urgent is CVE-2025-71263?

Priority 28/100. High severity

References

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