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Fencer Vulns
medium 6.5

CVE-2026-109088 json

libXtst RECORD EnableContext Reply Endless Loop

published 2026-10-27 13 d ago modified 2026-11-04 4 d ago also EUVD-2026-111114

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

A malicious X server could send malformed  RECORD EnableContext reolies that can cause a X client using the parse_reply_call_callback function in libXtst before 1.2.6 to enter a endless loop.

Patch / fix

  • X.org libXtst 1.2.6
  • libxtst Debian 14 2:1.2.6-1

debian advisories DEBIAN-CVE-2026-109088

  • libXtst openSUSE Tumbleweed 1.2.5-3.1

opensuse advisories openSUSE-SU-2026:12155-1

  • libxtst Alpine 3.24 1.2.6-r0

alpine advisories ALPINE-CVE-2026-109088

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libXtst Azure Linux 3.0 1.2.6-1

azure linux advisories AZL-111172

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-109088 updated cvss 6.5

libXtst: libXtst: Denial of Service via malformed RECORD EnableContext replies

  • Red Hat Enterprise Linux 6 libXtst, libXtst 1.2.4-9.el10
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 libXtst, libXtst 1.2.4-9.el10 Red Hat Enterprise Linux 8 libXtst, libXtst 1.2.4-9.el10 Red Hat Enterprise Linux 9 libXtst, libXtst 1.2.4-9.el10 Red Hat Enterprise Linux 10 libXtst 1.2.4-9.el10
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images libXtst 1.2.5-5.3.hum1
    fixed: vendor fix RHSA-2026:93594

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
5 d ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Affected products

  • X.org libXtst

Classification

Weakness
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.