Vulnerability · Published Sep 5, 2026 · Assigned by mitre
CVE-2026-86143
Medium 6.9
In plain English
A medium-severity security flaw in libxml2 from xmlsoft. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 9% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)6.9Medium
Exploit odds (30 days)0.2%top 90.9% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | libxml2 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 |
| AlmaLinux:8 | libxml2 | 2.9.7-21.el8_10.9 | ALSA-2026:71641 |
| AlmaLinux:9 | libxml2 | 2.9.13-14.el9_8.5 | ALSA-2026:71585 |
| AlmaLinux:10 | libxml2-devel | 2.12.5-10.el10_2.4 | ALSA-2026:71586 |
| AlmaLinux:8 | libxml2-devel | 2.9.7-21.el8_10.9 | ALSA-2026:71641 |
| AlmaLinux:9 | libxml2-devel | 2.9.13-14.el9_8.5 | ALSA-2026:71585 |
| AlmaLinux:10 | libxml2-static | 2.12.5-10.el10_2.4 | ALSA-2026:71586 |
| AlmaLinux:10 | python3-libxml2 | 2.12.5-10.el10_2.4 | ALSA-2026:71586 |
| AlmaLinux:8 | python3-libxml2 | 2.9.7-21.el8_10.9 | ALSA-2026:71641 |
| AlmaLinux:9 | python3-libxml2 | 2.9.13-14.el9_8.5 | ALSA-2026:71585 |
| Debian:12 | libxml2 | no fix listed | DEBIAN-CVE-2026-86143 |
| Debian:13 | libxml2 | no fix listed | DEBIAN-CVE-2026-86143 |
| Debian:14 | libxml2 | 2.15.4+dfsg-1 | DEBIAN-CVE-2026-86143 |
| Rocky Linux:10 | libxml2 | 0:2.12.5-10.el10_2.4 | RLSA-2026:71586 |
| Rocky Linux:8 | libxml2 | 0:2.9.7-21.el8_10.9 | RLSA-2026:71641 |
| Rocky Linux:9 | libxml2 | 0:2.9.13-14.el9_8.5 | RLSA-2026:71585 |
| Ubuntu:22.04:LTS | libxml2 | 2.9.13+dfsg-1ubuntu0.14 | UBUNTU-CVE-2026-86143 |
| Ubuntu:22.04:LTS | libxml2 | 2.9.13+dfsg-1ubuntu0.14 | USN-8910-1 |
| Ubuntu:24.04:LTS | libxml2 | 2.9.14+dfsg-1.3ubuntu3.10 | USN-8910-1 |
| Ubuntu:24.04:LTS | libxml2 | 2.9.14+dfsg-1.3ubuntu3.10 | UBUNTU-CVE-2026-86143 |
| Ubuntu:26.04:LTS | libxml2 | 2.15.2+dfsg-0.1ubuntu0.3 | USN-8910-1 |
| Ubuntu:26.04:LTS | libxml2 | 2.15.2+dfsg-0.1ubuntu0.3 | UBUNTU-CVE-2026-86143 |
Affected products (as reported)
Weakness: CWE-192 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L