CVE-2026-86143
In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling writecallback. This has security relevance for many types of uses of that length value within a callback.
CVE-2026-86143 is fixed in 11 products on 1 platform, first by RHSA-2026:89759, released August 28, 2026. It is not reported as exploited. Patch Radar priority: High.
High
CVSS
8.5
Moderate
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0019
9th percentile
In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse causes negative lengths to reach write callbacks, aka a lack of a check for integer overflow before calling writecallback. This has security relevance for many types of uses of that length value within a callback.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| libxml2 · Debian 14 | 2.15.4+dfsg-1 | DEBIAN-CVE-2026-86143 | Sep 11, 2026 |
| libxml2 · RHEL 10 | 2.12.5-9.el10_0.9 | RHSA-2026:89759 | Aug 28, 2026 |
| libxml2 · RHEL 8 | 0:2.9.7-21.el8_10.9 | RHSA-2026:71641 | Sep 24, 2026 |
| libxml2 · RHEL 9 | 0:2.9.13-14.el9_8.5 | RHSA-2026:71585 | Sep 25, 2026 |
| libxml2 · Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | libxml2 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | Oct 9, 2026 |
| libxml2 · Ubuntu 20.04 LTS (focal) | 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | libxml2 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | Oct 9, 2026 |
| libxml2 · Ubuntu 22.04.1 LTS (jammy) | 2.9.13+dfsg-1ubuntu0.14 | libxml2 2.9.13+dfsg-1ubuntu0.14 | Oct 9, 2026 |
| libxml2 · Ubuntu 24.04.5 LTS (noble) | 2.9.14+dfsg-1.3ubuntu3.10 | libxml2 2.9.14+dfsg-1.3ubuntu3.10 | Oct 9, 2026 |
| libxml2 · almalinux 10 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 | Sep 24, 2026 |
| libxml2 · almalinux 8 | 2.9.7-21.el8_10.9 | ALSA-2026:71641 | Sep 24, 2026 |
| libxml2 · almalinux 9 | 2.9.13-14.el9_8.5 | ALSA-2026:71585 | Sep 24, 2026 |
| libxml2 · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| libxml2 · ol 10 | 0:2.12.5-10.el10_2.4 | ELSA-2026-71586 | Sep 25, 2026 |
| libxml2 · ol 8 | 0:2.9.7-21.el8_10.9 | ELSA-2026-71641 | Sep 25, 2026 |
| libxml2 · ol 9 | 0:2.9.13-14.el9_8.5 | ELSA-2026-71585 | Sep 24, 2026 |
| libxml2 · rocky 10 | 0:2.12.5-10.el10_2.4 | RLSA-2026:71586 | Sep 25, 2026 |
| libxml2 · rocky 8 | 0:2.9.7-21.el8_10.9 | RLSA-2026:71641 | Sep 26, 2026 |
| libxml2 · rocky 9 | 0:2.9.13-14.el9_8.5 | RLSA-2026:71585 | Sep 25, 2026 |
| libxml2-16 · Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | libxml2-16 2.15.2+dfsg-0.1ubuntu0.3 | Sep 17, 2026 |
| libxml2-debuginfo · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| libxml2-debugsource · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| libxml2-devel · RHEL 8 | 0:2.9.7-21.el8_10.9 | RHSA-2026:71641 | Sep 24, 2026 |
| libxml2-devel · RHEL 9 | 0:2.9.13-14.el9_8.5 | RHSA-2026:71585 | Sep 25, 2026 |
| libxml2-devel · almalinux 10 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 | Sep 24, 2026 |
| libxml2-devel · almalinux 8 | 2.9.7-21.el8_10.9 | ALSA-2026:71641 | Sep 24, 2026 |
| libxml2-devel · almalinux 9 | 2.9.13-14.el9_8.5 | ALSA-2026:71585 | Sep 24, 2026 |
| libxml2-devel · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| libxml2-devel · ol 10 | 0:2.12.5-10.el10_2.4 | ELSA-2026-71586 | Sep 25, 2026 |
| libxml2-devel · ol 8 | 0:2.9.7-21.el8_10.9 | ELSA-2026-71641 | Sep 25, 2026 |
| libxml2-devel · ol 9 | 0:2.9.13-14.el9_8.5 | ELSA-2026-71585 | Sep 24, 2026 |
| libxml2-source · Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | libxml2-source 2.15.2+dfsg-0.1ubuntu0.3 | Sep 17, 2026 |
| libxml2-static · almalinux 10 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 | Sep 24, 2026 |
| libxml2-static · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| libxml2-static · ol 10 | 0:2.12.5-10.el10_2.4 | ELSA-2026-71586 | Sep 25, 2026 |
| libxml2-utils · Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | libxml2-utils 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | Oct 9, 2026 |
| libxml2-utils · Ubuntu 20.04 LTS (focal) | 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | libxml2-utils 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | Oct 9, 2026 |
| libxml2-utils · Ubuntu 22.04.1 LTS (jammy) | 2.9.13+dfsg-1ubuntu0.14 | libxml2-utils 2.9.13+dfsg-1ubuntu0.14 | Oct 9, 2026 |
| libxml2-utils · Ubuntu 24.04.5 LTS (noble) | 2.9.14+dfsg-1.3ubuntu3.10 | libxml2-utils 2.9.14+dfsg-1.3ubuntu3.10 | Oct 9, 2026 |
| libxml2-utils · Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | libxml2-utils 2.15.2+dfsg-0.1ubuntu0.3 | Sep 17, 2026 |
| python-libxml2 · Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | python-libxml2 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | Oct 9, 2026 |
| python-libxml2 · Ubuntu 20.04 LTS (focal) | 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | python-libxml2 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | Oct 9, 2026 |
| python3-libxml2 · RHEL 8 | 0:2.9.7-21.el8_10.9 | RHSA-2026:71641 | Sep 24, 2026 |
| python3-libxml2 · RHEL 9 | 0:2.9.13-14.el9_8.5 | RHSA-2026:71585 | Sep 25, 2026 |
| python3-libxml2 · Ubuntu 18.04.6 LTS (bionic) | 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | python3-libxml2 2.9.4+dfsg1-6.1ubuntu1.9+esm9 | Oct 9, 2026 |
| python3-libxml2 · Ubuntu 20.04 LTS (focal) | 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | python3-libxml2 2.9.10+dfsg-5ubuntu0.20.04.10+esm6 | Oct 9, 2026 |
| python3-libxml2 · Ubuntu 22.04.1 LTS (jammy) | 2.9.13+dfsg-1ubuntu0.14 | python3-libxml2 2.9.13+dfsg-1ubuntu0.14 | Oct 9, 2026 |
| python3-libxml2 · Ubuntu 24.04.5 LTS (noble) | 2.9.14+dfsg-1.3ubuntu3.10 | python3-libxml2 2.9.14+dfsg-1.3ubuntu3.10 | Oct 9, 2026 |
| python3-libxml2 · Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | python3-libxml2 2.15.2+dfsg-0.1ubuntu0.3 | Sep 17, 2026 |
| python3-libxml2 · almalinux 10 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 | Sep 24, 2026 |
| python3-libxml2 · almalinux 8 | 2.9.7-21.el8_10.9 | ALSA-2026:71641 | Sep 24, 2026 |
| python3-libxml2 · almalinux 9 | 2.9.13-14.el9_8.5 | ALSA-2026:71585 | Sep 24, 2026 |
| python3-libxml2 · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
| python3-libxml2 · ol 10 | 0:2.12.5-10.el10_2.4 | ELSA-2026-71586 | Sep 25, 2026 |
| python3-libxml2 · ol 8 | 0:2.9.7-21.el8_10.9 | ELSA-2026-71641 | Sep 25, 2026 |
| python3-libxml2 · ol 9 | 0:2.9.13-14.el9_8.5 | ELSA-2026-71585 | Sep 24, 2026 |
| python3-libxml2-debuginfo · amzn 2023 | 2.10.4-1.amzn2023.0.21 | ALAS2023-2026-3122 | Sep 28, 2026 |
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