# CVE-2026-86139: In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

CVE-2026-86139 is fixed in 5 products on 1 platform, first by DEBIAN-CVE-2026-86139, released September 11, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-86139
- Priority: High
- CVSS: 7.8 (Moderate)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 4, 2026
- Weakness: Integer Overflow or Wraparound
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-86139

## Description

In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxml2 Debian 14 | 2.15.4+dfsg-1 | [DEBIAN-CVE-2026-86139](https://patchblox.com/security/data/fix/linux/debian-cve-2026-86139.md) | Sep 11, 2026 |
| Linux | libxml2-16 Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | [libxml2-16 2.15.2+dfsg-0.1ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libxml2-16-2.15.2-dfsg-0.1ubuntu0.3.md) | Sep 17, 2026 |
| Linux | libxml2-source Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | [libxml2-source 2.15.2+dfsg-0.1ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libxml2-source-2.15.2-dfsg-0.1ubuntu0.3.md) | Sep 17, 2026 |
| Linux | libxml2-utils Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | [libxml2-utils 2.15.2+dfsg-0.1ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libxml2-utils-2.15.2-dfsg-0.1ubuntu0.3.md) | Sep 17, 2026 |
| Linux | python3-libxml2 Ubuntu 26.04.1 LTS (resolute) | 2.15.2+dfsg-0.1ubuntu0.3 | [python3-libxml2 2.15.2+dfsg-0.1ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-python3-libxml2-2.15.2-dfsg-0.1ubuntu0.3.md) | Sep 17, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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