# CVE-2026-86137: In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the NXT macro in xmlregexp.

CVE-2026-86137 is fixed in 7 products on 1 platform, first by DEBIAN-CVE-2026-86137, released September 11, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-86137
- Priority: Routine
- CVSS: 6.1 (Low)
- EPSS: 0.0020
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 5, 2026
- Weakness: Out-of-bounds Read
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-86137

## Description

In libxml2 before 2.15.4, xmlFAParsePosCharGroup has an out-of-bounds read, aka an out-of-bounds read in the NXT macro in xmlregexp.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxml2 Debian 14 | 2.15.4+dfsg-1 | [DEBIAN-CVE-2026-86137](https://patchblox.com/security/data/fix/linux/debian-cve-2026-86137.md) | Sep 11, 2026 |
| Linux | libxml2 amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | libxml2-debuginfo amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | libxml2-debugsource amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | libxml2-devel amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | libxml2-static amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | python3-libxml2 amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |
| Linux | python3-libxml2-debuginfo amzn 2023 | 2.10.4-1.amzn2023.0.21 | [ALAS2023-2026-3122](https://patchblox.com/security/data/fix/linux/alas2023-2026-3122.md) | Sep 28, 2026 |

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Data as of 2026-11-08T13:06:02Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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