CVE-2026-88806
published 2026-09-21CVE-2026-88806: A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
PriorityP344high7.5CVSS 3.1
AVNACHPRNUIRSUCHIHAH
EPSS
0.20%
8.9th percentile
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
Affected
2 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| x.org | libx11 | < 1.8.14 | 1.8.14 |
| x.org | libx11 | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
vendor_redhat7.5HIGH
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GHSA
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
ghsa_unreviewed·2026-09-21
CVE-2026-88806 [HIGH] CWE-122 A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
Red Hat
libX11: libX11: Heap-based buffer overflow via malicious X server
vendor_redhat·2026-09-21·CVSS 7.5
CVE-2026-88806 [HIGH] CWE-787 libX11: libX11: Heap-based buffer overflow via malicious X server
libX11: libX11: Heap-based buffer overflow via malicious X server
A malicious X server could exploit a buffer overflow in libX11 before 1.8.14 during handling of XkbGetMap overflowing the key_sym_map.
A flaw was found in libX11. A heap-based buffer overflow vulnerability exists during the handling of XkbGetMap replies. A remote attacker, by operating a malicious X server, could exploit this flaw to potentially execute arbitrary code or cause a denial of service on the client system. User interaction is required for exploitation.
Mitigation: To mitigate this issue, users should avoid connecting to untrusted X servers. When using SSH, ensure that X11 forwarding (`ssh -X` or `ssh -Y`) is only enabled for trusted remote hosts. To prevent X11 forwarding for specific hosts, add `ForwardX11 no
No detection rules found.
No public exploits indexed.
2026-09-21
Published