High severity · published Sep 21, 2026
CVE-2026-88806
libX11 XkbGetMap Reply Heap-based Buffer Overflow
7.5
CVSS
0.2%
EPSS
No
On KEV
Description
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
Required
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 10% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
libX11 · x.org
before 1.8.14 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-88806
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-88806
gitlab.freedesktop.org
https://gitlab.freedesktop.org/xorg/lib/libx11/-/merge_requests/309
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