Description
A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.
Affected products
x.org: x server; redhat: enterprise linux
References10
- access.redhat.com/errata/RHSA-2026:20547
- access.redhat.com/errata/RHSA-2026:20555
- access.redhat.com/errata/RHSA-2026:20557
- access.redhat.com/errata/RHSA-2026:20558
- access.redhat.com/errata/RHSA-2026:20560
- access.redhat.com/errata/RHSA-2026:20561
- access.redhat.com/errata/RHSA-2026:20562
- access.redhat.com/errata/RHSA-2026:20563
- access.redhat.com/errata/RHSA-2026:20575
- access.redhat.com/errata/RHSA-2026:20576
Metrics
- CVSS 3.1
-
9.1
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H - EPSS — exploit probability
- 0% percentile: 43 · as of 13 November 2026
- CWE
- CWE-805
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.