# CVE-2026-77214: libexpat Heap Buffer Over-read in xmlparse.c via XML_ParseBuffer CVE-2026-77214 is fixed in 3 products on 1 platform, first by DEBIAN-CVE-2026-77214, released October 10, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-77214 - Priority: High - CVSS: 8.2 (Important) - EPSS: 0.0032 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 7, 2026 - Weakness: Out-of-bounds Read - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-77214 ## Description libexpat before commit 13c5f63 contains a heap buffer over-read vulnerability in xmlparse.c. XML_ParseBuffer advances the parse buffer end with parser->m_bufferEnd += len using a caller-supplied length that is not validated against the allocated buffer size, so repeated XML_ParseBuffer calls move m_bufferEnd past the end of the heap allocation and subsequent parsing reads out of bounds. Reaching this path requires a parse buffer to already be present; otherwise XML_ParseBuffer returns XML_ERROR_NO_BUFFER. A buffer is present after a prior call to XML_GetBuffer, either directly (the common case) or indirectly through a prior XML_Parse call that allocates the buffer internally. The over-read discloses adjacent heap memory to the calling application, recovering heap pointers, libc function pointers, and code pointers sufficient to defeat ASLR and build further exploitation primitives. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | expat Debian 12.15 (bookworm) | 2.5.0-1+deb12u5 | [DEBIAN-CVE-2026-77214](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77214.md) | Oct 10, 2026 | | Linux | expat Debian 13.5 (trixie) | 2.9.0-1~deb13u1 | [DEBIAN-CVE-2026-77214](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77214.md) | Oct 10, 2026 | | Linux | expat Debian 14 | 2.9.0-1 | [DEBIAN-CVE-2026-77214](https://patchblox.com/security/data/fix/linux/debian-cve-2026-77214.md) | Oct 10, 2026 | | Linux | expat RHEL 10 | 2.7.3-1.el10_2.7 | [RHSA-2026:88248](https://patchblox.com/security/data/fix/linux/rhsa-2026-88248.md) | Oct 24, 2026 | | Linux | expat RHEL 8 | 0:2.5.0-6.el8_10 | [RHSA-2026:92323](https://patchblox.com/security/data/fix/linux/rhsa-2026-92323.md) | Oct 30, 2026 | | Linux | expat RHEL 9 | 0:2.5.0-6.el9_8.7 | [RHSA-2026:88247](https://patchblox.com/security/data/fix/linux/rhsa-2026-88247.md) | Oct 24, 2026 | | Linux | expat almalinux 10 | 2.7.3-1.el10_2.7 | [ALSA-2026:88248](https://patchblox.com/security/data/fix/linux/alsa-2026-88248.md) | Nov 7, 2026 | | Linux | expat almalinux 8 | 2.5.0-6.el8_10 | [ALSA-2026:92323](https://patchblox.com/security/data/fix/linux/alsa-2026-92323.md) | Nov 7, 2026 | | Linux | expat almalinux 9 | 2.5.0-6.el9_8.7 | [ALSA-2026:88247](https://patchblox.com/security/data/fix/linux/alsa-2026-88247.md) | Nov 7, 2026 | | Linux | expat ol 10 | 0:2.7.3-1.el10_2.7 | [ELSA-2026-88248](https://patchblox.com/security/data/fix/linux/elsa-2026-88248.md) | Nov 7, 2026 | | Linux | expat ol 8 | 0:2.5.0-6.el8_10 | [ELSA-2026-92323](https://patchblox.com/security/data/fix/linux/elsa-2026-92323.md) | Nov 7, 2026 | | Linux | expat ol 9 | 0:2.5.0-6.el9_8.7 | [ELSA-2026-88247](https://patchblox.com/security/data/fix/linux/elsa-2026-88247.md) | Nov 7, 2026 | | Linux | expat opensuse-leap 16.0 | 2.8.5-160000.1.1 | [OPENSUSE-SU-2026:22177-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22177-1.md) | Nov 7, 2026 | | Linux | expat rocky 10 | 0:2.7.3-1.el10_2.7 | [RLSA-2026:88248](https://patchblox.com/security/data/fix/linux/rlsa-2026-88248.md) | Nov 7, 2026 | | Linux | expat rocky 8 | 0:2.5.0-6.el8_10 | [RLSA-2026:92323](https://patchblox.com/security/data/fix/linux/rlsa-2026-92323.md) | Nov 7, 2026 | | Linux | expat rocky 9 | 0:2.5.0-6.el9_8.7 | [RLSA-2026:88247](https://patchblox.com/security/data/fix/linux/rlsa-2026-88247.md) | Nov 7, 2026 | | Linux | expat sles 15.6 | 2.8.5-150400.3.40.1 | [SUSE-SU-2026:4623-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4623-1.md) | Nov 7, 2026 | | Linux | expat sles 15.7 | 2.8.5-150700.3.15.1 | [SUSE-SU-2026:4619-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4619-1.md) | Nov 7, 2026 | | Linux | expat sles 16.0 | 2.8.5-160000.1.1 | [SUSE-SU-2026:24469-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24469-1.md) | Nov 7, 2026 | | Linux | expat-devel RHEL 8 | 0:2.5.0-6.el8_10 | [RHSA-2026:92323](https://patchblox.com/security/data/fix/linux/rhsa-2026-92323.md) | Oct 30, 2026 | | Linux | expat-devel RHEL 9 | 0:2.5.0-6.el9_8.7 | [RHSA-2026:88247](https://patchblox.com/security/data/fix/linux/rhsa-2026-88247.md) | Oct 24, 2026 | | Linux | expat-devel almalinux 8 | 2.5.0-6.el8_10 | [ALSA-2026:92323](https://patchblox.com/security/data/fix/linux/alsa-2026-92323.md) | Nov 7, 2026 | | Linux | expat-devel almalinux 9 | 2.5.0-6.el9_8.7 | [ALSA-2026:88247](https://patchblox.com/security/data/fix/linux/alsa-2026-88247.md) | Nov 7, 2026 | | Linux | expat-devel ol 10 | 0:2.7.3-1.el10_2.7 | [ELSA-2026-88248](https://patchblox.com/security/data/fix/linux/elsa-2026-88248.md) | Nov 7, 2026 | | Linux | expat-devel ol 8 | 0:2.5.0-6.el8_10 | [ELSA-2026-92323](https://patchblox.com/security/data/fix/linux/elsa-2026-92323.md) | Nov 7, 2026 | | Linux | expat-devel ol 9 | 0:2.5.0-6.el9_8.7 | [ELSA-2026-88247](https://patchblox.com/security/data/fix/linux/elsa-2026-88247.md) | Nov 7, 2026 | | Linux | firefox RHEL 10 | 153.5.0-1.el10_2 | [RHSA-2026:89758](https://patchblox.com/security/data/fix/linux/rhsa-2026-89758.md) | Oct 31, 2026 | | Linux | firefox almalinux 10 | 153.5.0-1.el10_2 | [ALSA-2026:89758](https://patchblox.com/security/data/fix/linux/alsa-2026-89758.md) | Nov 7, 2026 | | Linux | firefox ol 10 | 0:153.5.0-1.0.1.el10_2 | [ELSA-2026-89758](https://patchblox.com/security/data/fix/linux/elsa-2026-89758.md) | Nov 7, 2026 | | Linux | firefox rocky 10 | 0:153.5.0-1.el10_2 | [RLSA-2026:89758](https://patchblox.com/security/data/fix/linux/rlsa-2026-89758.md) | Nov 7, 2026 | --- Data as of 2026-11-09T01:18:40Z UTC. 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