# CVE-2026-55999: xorg-x11-server-Xwayland: Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwaylan... CVE-2026-55999 is fixed in 21 products on 1 platform, first by SUSE-SU-2026:2786-1, released July 8, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-55999 - Priority: High - CVSS: 7.8 (important) - EPSS: 0.0033 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jul 8, 2026 ## Description Local attackers with a X connection able to provide PCX fonts to the X server xorg-server before 21.2.24 and xwayland before 24.1.13 could cause a heap buffer overflow via SetFont due to missing glyph boundary checks. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | xorg-server Debian 13.5 (trixie) | 2:21.1.16-1.3+deb13u4 | [DEBIAN-CVE-2026-55999](https://patchblox.com/security/data/fix/linux/debian-cve-2026-55999.md) | Jul 8, 2026 | | Linux | xorg-server Debian 14 | 2:21.1.24-1 | [DEBIAN-CVE-2026-55999](https://patchblox.com/security/data/fix/linux/debian-cve-2026-55999.md) | Jul 8, 2026 | | Linux | xorg-x11-server opensuse-leap 16.0 | 21.1.15-160000.6.1 | [OPENSUSE-SU-2026:21273-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21273-1.md) | Jul 8, 2026 | | Linux | xorg-x11-server rocky 8 | 0:1.20.11-28.el8_10.3 | [RLSA-2026:38487](https://patchblox.com/security/data/fix/linux/rlsa-2026-38487.md) | Jul 14, 2026 | | Linux | xorg-x11-server rocky 9 | 0:1.20.11-34.el9_8.3 | [RLSA-2026:38486](https://patchblox.com/security/data/fix/linux/rlsa-2026-38486.md) | Jul 14, 2026 | | Linux | xorg-x11-server sles 15.6 | 21.1.11-150600.5.31.1 | [SUSE-SU-2026:2786-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2786-1.md) | Jul 8, 2026 | | Linux | xorg-x11-server sles 15.7 | 21.1.15-150700.5.22.1 | [SUSE-SU-2026:2788-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2788-1.md) | Jul 8, 2026 | | Linux | xorg-x11-server-Xdmx RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xdmx RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xdmx almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xdmx almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xdmx ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xdmx ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xephyr ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xephyr ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xephyr-debuginfo amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xnest RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xnest RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xnest almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xnest almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xnest amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xnest ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xnest ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xnest-debuginfo amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xorg RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xorg RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xorg almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xorg almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xorg amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xorg ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xorg ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xorg-debuginfo amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xvfb RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xvfb RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xvfb almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xvfb almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xvfb amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xvfb ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xvfb ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xvfb-debuginfo amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xwayland RHEL 10 | 24.1.5-6.el10_0.2 | [RHSA-2026:50100](https://patchblox.com/security/data/fix/linux/rhsa-2026-50100.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland RHEL 8 | 0:21.1.3-20.el8_10.3 | [RHSA-2026:38488](https://patchblox.com/security/data/fix/linux/rhsa-2026-38488.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland RHEL 9 | 0:24.1.9-4.el9_8.3 | [RHSA-2026:38490](https://patchblox.com/security/data/fix/linux/rhsa-2026-38490.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland almalinux 10 | 24.1.9-4.el10_2.3 | [ALSA-2026:38489](https://patchblox.com/security/data/fix/linux/alsa-2026-38489.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland almalinux 8 | 21.1.3-20.el8_10.3 | [ALSA-2026:38488](https://patchblox.com/security/data/fix/linux/alsa-2026-38488.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland almalinux 9 | 24.1.9-4.el9_8.3 | [ALSA-2026:38490](https://patchblox.com/security/data/fix/linux/alsa-2026-38490.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland amzn 2023 | 24.1.3-1.amzn2023.0.6 | [ALAS2023-2026-1944](https://patchblox.com/security/data/fix/linux/alas2023-2026-1944.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xwayland ol 10 | 0:24.1.9-4.el10_2.3 | [ELSA-2026-38489](https://patchblox.com/security/data/fix/linux/elsa-2026-38489.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xwayland ol 8 | 0:21.1.3-20.el8_10.3 | [ELSA-2026-38488](https://patchblox.com/security/data/fix/linux/elsa-2026-38488.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland ol 9 | 0:24.1.9-4.el9_8.3 | [ELSA-2026-38490](https://patchblox.com/security/data/fix/linux/elsa-2026-38490.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xwayland rocky 10 | 0:24.1.9-4.el10_2.3 | [RLSA-2026:38489](https://patchblox.com/security/data/fix/linux/rlsa-2026-38489.md) | Jul 14, 2026 | | Linux | xorg-x11-server-Xwayland rocky 8 | 0:21.1.3-20.el8_10.3 | [RLSA-2026:38488](https://patchblox.com/security/data/fix/linux/rlsa-2026-38488.md) | Jul 14, 2026 | | Linux | xorg-x11-server-Xwayland rocky 9 | 0:24.1.9-4.el9_8.3 | [RLSA-2026:38490](https://patchblox.com/security/data/fix/linux/rlsa-2026-38490.md) | Jul 14, 2026 | | Linux | xorg-x11-server-Xwayland-debuginfo amzn 2023 | 24.1.3-1.amzn2023.0.6 | [ALAS2023-2026-1944](https://patchblox.com/security/data/fix/linux/alas2023-2026-1944.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xwayland-debugsource amzn 2023 | 24.1.3-1.amzn2023.0.6 | [ALAS2023-2026-1944](https://patchblox.com/security/data/fix/linux/alas2023-2026-1944.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xwayland-devel RHEL 9 | 0:24.1.9-4.el9_8.3 | [RHSA-2026:38490](https://patchblox.com/security/data/fix/linux/rhsa-2026-38490.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland-devel almalinux 10 | 24.1.9-4.el10_2.3 | [ALSA-2026:38489](https://patchblox.com/security/data/fix/linux/alsa-2026-38489.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland-devel almalinux 9 | 24.1.9-4.el9_8.3 | [ALSA-2026:38490](https://patchblox.com/security/data/fix/linux/alsa-2026-38490.md) | Jul 13, 2026 | | Linux | xorg-x11-server-Xwayland-devel amzn 2023 | 24.1.3-1.amzn2023.0.6 | [ALAS2023-2026-1944](https://patchblox.com/security/data/fix/linux/alas2023-2026-1944.md) | Jul 20, 2026 | | Linux | xorg-x11-server-Xwayland-devel ol 10 | 0:24.1.9-4.el10_2.3 | [ELSA-2026-38489](https://patchblox.com/security/data/fix/linux/elsa-2026-38489.md) | Sep 1, 2026 | | Linux | xorg-x11-server-Xwayland-devel ol 9 | 0:24.1.9-4.el9_8.3 | [ELSA-2026-38490](https://patchblox.com/security/data/fix/linux/elsa-2026-38490.md) | Sep 1, 2026 | | Linux | xorg-x11-server-common RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-common RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-common almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-common almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-common amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-common ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-common ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-debuginfo amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-debugsource amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-devel RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-devel RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-devel almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-devel almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-devel amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-devel ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-devel ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-source RHEL 8 | 0:1.20.11-28.el8_10.3 | [RHSA-2026:38487](https://patchblox.com/security/data/fix/linux/rhsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-source RHEL 9 | 0:1.20.11-34.el9_8.3 | [RHSA-2026:38486](https://patchblox.com/security/data/fix/linux/rhsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-source almalinux 8 | 1.20.11-28.el8_10.3 | [ALSA-2026:38487](https://patchblox.com/security/data/fix/linux/alsa-2026-38487.md) | Jul 13, 2026 | | Linux | xorg-x11-server-source almalinux 9 | 1.20.11-34.el9_8.3 | [ALSA-2026:38486](https://patchblox.com/security/data/fix/linux/alsa-2026-38486.md) | Jul 13, 2026 | | Linux | xorg-x11-server-source amzn 2023 | 21.1.13-5.amzn2023.0.11 | [ALAS2023-2026-1943](https://patchblox.com/security/data/fix/linux/alas2023-2026-1943.md) | Jul 20, 2026 | | Linux | xorg-x11-server-source ol 8 | 0:1.20.11-28.el8_10.3 | [ELSA-2026-38487](https://patchblox.com/security/data/fix/linux/elsa-2026-38487.md) | Sep 1, 2026 | | Linux | xorg-x11-server-source ol 9 | 0:1.20.11-34.el9_8.3 | [ELSA-2026-38486](https://patchblox.com/security/data/fix/linux/elsa-2026-38486.md) | Jul 13, 2026 | | Linux | xwayland Debian 14 | 2:24.1.13-1 | [DEBIAN-CVE-2026-55999](https://patchblox.com/security/data/fix/linux/debian-cve-2026-55999.md) | Jul 8, 2026 | | Linux | xwayland opensuse-leap 16.0 | 24.1.6-160000.6.1 | [OPENSUSE-SU-2026:21283-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21283-1.md) | Jul 10, 2026 | | Linux | xwayland sles 15.7 | 24.1.5-150700.3.22.1 | [SUSE-SU-2026:2787-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-2787-1.md) | Jul 8, 2026 | | Linux | xwayland sles 16.0 | 24.1.6-160000.6.1 | [SUSE-SU-2026:22617-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-22617-1.md) | Jul 10, 2026 | --- Data as of 2026-11-09T13:31:49Z UTC. 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