# CVE-2026-56132: In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.

CVE-2026-56132 is fixed in 11 products on 1 platform, first by RHSA-2026:64810, released June 19, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-56132
- Priority: Routine
- CVSS: 6.9 (Moderate)
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 18, 2026
- Weakness: Incorrect Synchronization
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-56132

## Description

In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | MozillaFirefox opensuse-leap 16.0 | 153.5.0-160000.1.1 | [OPENSUSE-SU-2026:22139-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22139-1.md) | Nov 7, 2026 |
| Linux | MozillaFirefox sles 15.6 | 153.5.0-150400.157.16.1 | [SUSE-SU-2026:4834-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4834-1.md) | Nov 7, 2026 |
| Linux | MozillaFirefox sles 15.7 | 153.5.0-150400.157.16.1 | [SUSE-SU-2026:4834-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4834-1.md) | Nov 7, 2026 |
| Linux | MozillaFirefox sles 16.0 | 153.5.0-160000.1.1 | [SUSE-SU-2026:24260-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24260-1.md) | Nov 7, 2026 |
| Linux | MozillaThunderbird sles 15.7 | 153.5.0-150400.13.9.1 | [SUSE-SU-2026:4736-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4736-1.md) | Nov 7, 2026 |
| Linux | expat Debian 12.15 (bookworm) | 2.5.0-1+deb12u5 | [DEBIAN-CVE-2026-56132](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56132.md) | Jun 28, 2026 |
| Linux | expat Debian 13.5 (trixie) | 2.8.2-1~deb13u1 | [DEBIAN-CVE-2026-56132](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56132.md) | Jun 28, 2026 |
| Linux | expat Debian 14 | 2.8.2-1 | [DEBIAN-CVE-2026-56132](https://patchblox.com/security/data/fix/linux/debian-cve-2026-56132.md) | Jun 28, 2026 |
| Linux | expat RHEL 10 | 2.7.3-1.el10_2.3 | [RHSA-2026:64810](https://patchblox.com/security/data/fix/linux/rhsa-2026-64810.md) | Jun 19, 2026 |
| Linux | expat RHEL 8 | 0:2.5.0-2.el8_10.2 | [RHSA-2026:64809](https://patchblox.com/security/data/fix/linux/rhsa-2026-64809.md) | Sep 13, 2026 |
| Linux | expat RHEL 9 | 0:2.5.0-6.el9_8.3 | [RHSA-2026:64812](https://patchblox.com/security/data/fix/linux/rhsa-2026-64812.md) | Sep 13, 2026 |
| Linux | expat Ubuntu 18.04.6 LTS (bionic) | 2.2.5-3ubuntu0.9+esm5 | [expat 2.2.5-3ubuntu0.9+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-expat-2.2.5-3ubuntu0.9-esm5.md) | Aug 20, 2026 |
| Linux | expat Ubuntu 20.04 LTS (focal) | 2.2.9-1ubuntu0.8+esm3 | [expat 2.2.9-1ubuntu0.8+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-expat-2.2.9-1ubuntu0.8-esm3.md) | Aug 20, 2026 |
| Linux | expat Ubuntu 22.04.1 LTS (jammy) | 2.4.7-1ubuntu0.9 | [expat 2.4.7-1ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-expat-2.4.7-1ubuntu0.9.md) | Aug 20, 2026 |
| Linux | expat Ubuntu 24.04.5 LTS (noble) | 2.6.1-2ubuntu0.6 | [expat 2.6.1-2ubuntu0.6](https://patchblox.com/security/data/fix/linux/ubuntu-noble-expat-2.6.1-2ubuntu0.6.md) | Aug 20, 2026 |
| Linux | expat Ubuntu 26.04.1 LTS (resolute) | 2.7.4-1ubuntu0.2 | [expat 2.7.4-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-expat-2.7.4-1ubuntu0.2.md) | Aug 20, 2026 |
| Linux | expat almalinux 10 | 2.7.3-1.el10_2.3 | [ALSA-2026:64810](https://patchblox.com/security/data/fix/linux/alsa-2026-64810.md) | Sep 8, 2026 |
| Linux | expat almalinux 8 | 2.5.0-2.el8_10.2 | [ALSA-2026:64809](https://patchblox.com/security/data/fix/linux/alsa-2026-64809.md) | Sep 8, 2026 |
| Linux | expat almalinux 9 | 2.5.0-6.el9_8.3 | [ALSA-2026:64812](https://patchblox.com/security/data/fix/linux/alsa-2026-64812.md) | Sep 8, 2026 |
| Linux | expat amzn 2023 | 2.6.3-1.amzn2023.0.5 | [ALAS2023-2026-1900](https://patchblox.com/security/data/fix/linux/alas2023-2026-1900.md) | Jul 6, 2026 |
| Linux | expat ol 10 | 0:2.7.3-1.el10_2.3 | [ELSA-2026-64810-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64810-0.md) | Sep 8, 2026 |
| Linux | expat ol 8 | 0:2.5.0-2.el8_10.2 | [ELSA-2026-64809-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64809-0.md) | Sep 8, 2026 |
| Linux | expat ol 9 | 0:2.5.0-6.el9_8.3 | [ELSA-2026-64812-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64812-0.md) | Sep 8, 2026 |
| Linux | expat opensuse-leap 16.0 | 2.8.4-160000.1.1 | [OPENSUSE-SU-2026:21945-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21945-1.md) | Sep 24, 2026 |
| Linux | expat rocky 10 | 0:2.7.3-1.el10_2.3 | [RLSA-2026:64810](https://patchblox.com/security/data/fix/linux/rlsa-2026-64810.md) | Sep 9, 2026 |
| Linux | expat rocky 8 | 0:2.5.0-2.el8_10.2 | [RLSA-2026:64809](https://patchblox.com/security/data/fix/linux/rlsa-2026-64809.md) | Sep 9, 2026 |
| Linux | expat rocky 9 | 0:2.5.0-6.el9_8.3 | [RLSA-2026:64812](https://patchblox.com/security/data/fix/linux/rlsa-2026-64812.md) | Sep 9, 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 | 2.8.4-160000.1.1 | [SUSE-SU-2026:23912-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23912-1.md) | Sep 24, 2026 |
| Linux | expat-debuginfo amzn 2023 | 2.6.3-1.amzn2023.0.5 | [ALAS2023-2026-1900](https://patchblox.com/security/data/fix/linux/alas2023-2026-1900.md) | Jul 6, 2026 |
| Linux | expat-debugsource amzn 2023 | 2.6.3-1.amzn2023.0.5 | [ALAS2023-2026-1900](https://patchblox.com/security/data/fix/linux/alas2023-2026-1900.md) | Jul 6, 2026 |
| Linux | expat-devel RHEL 8 | 0:2.5.0-2.el8_10.2 | [RHSA-2026:64809](https://patchblox.com/security/data/fix/linux/rhsa-2026-64809.md) | Sep 13, 2026 |
| Linux | expat-devel RHEL 9 | 0:2.5.0-6.el9_8.3 | [RHSA-2026:64812](https://patchblox.com/security/data/fix/linux/rhsa-2026-64812.md) | Sep 13, 2026 |
| Linux | expat-devel almalinux 10 | 2.7.3-1.el10_2.3 | [ALSA-2026:64810](https://patchblox.com/security/data/fix/linux/alsa-2026-64810.md) | Sep 8, 2026 |
| Linux | expat-devel almalinux 8 | 2.5.0-2.el8_10.2 | [ALSA-2026:64809](https://patchblox.com/security/data/fix/linux/alsa-2026-64809.md) | Sep 8, 2026 |
| Linux | expat-devel almalinux 9 | 2.5.0-6.el9_8.3 | [ALSA-2026:64812](https://patchblox.com/security/data/fix/linux/alsa-2026-64812.md) | Sep 8, 2026 |
| Linux | expat-devel amzn 2023 | 2.6.3-1.amzn2023.0.5 | [ALAS2023-2026-1900](https://patchblox.com/security/data/fix/linux/alas2023-2026-1900.md) | Jul 6, 2026 |
| Linux | expat-devel ol 10 | 0:2.7.3-1.el10_2.3 | [ELSA-2026-64810-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64810-0.md) | Sep 8, 2026 |
| Linux | expat-devel ol 8 | 0:2.5.0-2.el8_10.2 | [ELSA-2026-64809-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64809-0.md) | Sep 8, 2026 |
| Linux | expat-devel ol 9 | 0:2.5.0-6.el9_8.3 | [ELSA-2026-64812-0](https://patchblox.com/security/data/fix/linux/elsa-2026-64812-0.md) | Sep 8, 2026 |
| Linux | expat-static amzn 2023 | 2.6.3-1.amzn2023.0.5 | [ALAS2023-2026-1900](https://patchblox.com/security/data/fix/linux/alas2023-2026-1900.md) | Jul 6, 2026 |
| Linux | firefox amzn 2023 | 140.12.0-1.amzn2023.0.1 | [ALAS2023-2026-1928](https://patchblox.com/security/data/fix/linux/alas2023-2026-1928.md) | Jul 6, 2026 |
| Linux | firefox-debuginfo amzn 2023 | 140.12.0-1.amzn2023.0.1 | [ALAS2023-2026-1928](https://patchblox.com/security/data/fix/linux/alas2023-2026-1928.md) | Jul 6, 2026 |
| Linux | firefox-debugsource amzn 2023 | 140.12.0-1.amzn2023.0.1 | [ALAS2023-2026-1928](https://patchblox.com/security/data/fix/linux/alas2023-2026-1928.md) | Jul 6, 2026 |
| Linux | libexpat1 Ubuntu 18.04.6 LTS (bionic) | 2.2.5-3ubuntu0.9+esm5 | [libexpat1 2.2.5-3ubuntu0.9+esm5](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libexpat1-2.2.5-3ubuntu0.9-esm5.md) | Aug 20, 2026 |
| Linux | libexpat1 Ubuntu 20.04 LTS (focal) | 2.2.9-1ubuntu0.8+esm3 | [libexpat1 2.2.9-1ubuntu0.8+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libexpat1-2.2.9-1ubuntu0.8-esm3.md) | Aug 20, 2026 |
| Linux | libexpat1 Ubuntu 22.04.1 LTS (jammy) | 2.4.7-1ubuntu0.9 | [libexpat1 2.4.7-1ubuntu0.9](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libexpat1-2.4.7-1ubuntu0.9.md) | Aug 20, 2026 |
| Linux | libexpat1 Ubuntu 24.04.5 LTS (noble) | 2.6.1-2ubuntu0.6 | [libexpat1 2.6.1-2ubuntu0.6](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libexpat1-2.6.1-2ubuntu0.6.md) | Aug 20, 2026 |
| Linux | libexpat1 Ubuntu 26.04.1 LTS (resolute) | 2.7.4-1ubuntu0.2 | [libexpat1 2.7.4-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libexpat1-2.7.4-1ubuntu0.2.md) | Aug 20, 2026 |

---

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