CVE-2021-4008

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-12-17 · updated 2026-06-17
Weakness: CWE-119

Description

A flaw was found in xorg-x11-server in versions before 21.1.2 and before 1.20.14. An out-of-bounds access can occur in the SProcRenderCompositeGlyphs function. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Affected products

Debian Linux: 9.0, 10.0, 11.0
Fedoraproject Fedora: 34, 35
xorg-x11-server: before 1.20.14; 21.1.0, 21.1.1 — fixed in 1.20.14

How to fix

Upgrade to a fixed version: xorg-x11-server 1.20.14. Check the vendor advisory for mitigations.

References

https://lists.debian.org/debian-lts-announce/2021/12/msg00035.html
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NKLSZCY47QK4RCJFXITYFALCGPJAFXOK/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/NXTRPFEQLFZ6NT2LPLZEID664RGC3OCC/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PDHYZM6FII35JA7J275MFCJO6ADJUPQX/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T57DCF726O5LLTST4NBL5PQ7DLPB46HT/
https://lists.x.org/archives/xorg-announce/2021-December/003122.html
https://lists.x.org/archives/xorg-announce/2021-December/003124.html
https://security.gentoo.org/glsa/202305-30
https://security.netapp.com/advisory/ntap-20220114-0004/
https://www.debian.org/security/2021/dsa-5027
https://www.zerodayinitiative.com/advisories/ZDI-21-1547/
https://lists.debian.org/debian-lts-announce/2021/12/msg00035.html

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