USN-8913-1

Adam Bedard discovered that libx11 incorrectly handled certain XKB keyboard map replies. If a user were tricked into connecting to a malicious X server, a remote attacker could possibly use this issue to cause libx11 to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2026-88806) It was discovered that libx11 incorrectly handled certain X Input Method (XIM) messages. If a user were tricked into connecting to a malicious X server, a remote attacker could possibly use these issues to cause libx11 to crash, resulting in a denial of service. (CVE-2026-94283, CVE-2026-94284) It was discovered that libx11 incorrectly handled converting certain multibyte text. An attacker could possibly use this issue to cause libx11 to crash, resulting in a denial of service. (CVE-2026-94285) Update Instructions: Run `sudo pro fix USN-8913-1` to fix the vulnerability. The problem can be corrected by updating your system to the following package versions: libx11-6 - 2:1.8.13-1ubuntu0.1 libx11-data - 2:1.8.13-1ubuntu0.1 libx11-xcb1 - 2:1.8.13-1ubuntu0.1 No subscription required

Upstream Advisory

• View official advisory

Affected Packages

• libx11-6 2:1.8.13-1ubuntu0.1-2:1.8.13-1ubuntu0.1

• libx11-data 2:1.8.13-1ubuntu0.1-2:1.8.13-1ubuntu0.1

• libx11-xcb1 2:1.8.13-1ubuntu0.1-2:1.8.13-1ubuntu0.1

• libx11-6 2:1.7.5-1ubuntu0.4-2:1.7.5-1ubuntu0.4

• libx11-data 2:1.7.5-1ubuntu0.4-2:1.7.5-1ubuntu0.4

• libx11-xcb1 2:1.7.5-1ubuntu0.4-2:1.7.5-1ubuntu0.4

• libx11-xcb1 2:1.8.7-1ubuntu0.1-2:1.8.7-1ubuntu0.1

• libx11-6 2:1.8.7-1ubuntu0.1-2:1.8.7-1ubuntu0.1

• libx11-data 2:1.8.7-1ubuntu0.1-2:1.8.7-1ubuntu0.1

• libx11-6 2:1.6.9-2ubuntu1.6+esm1-2:1.6.9-2ubuntu1.6+esm1

• libx11-data 2:1.6.9-2ubuntu1.6+esm1-2:1.6.9-2ubuntu1.6+esm1

• libx11-xcb1 2:1.6.9-2ubuntu1.6+esm1-2:1.6.9-2ubuntu1.6+esm1