# CVE-2025-12863: Libxml2: namespace use-after-free in xmlsettreedoc() function of libxml2

CVE-2025-12863 is fixed in libxml2 on 1 platform by DEBIAN-CVE-2025-12863 (version 2.15.1+dfsg-0.4), released November 7, 2025. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2025-12863
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: n/a
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 7, 2025
- Weakness: Use After Free
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-12863

## Description

A flaw was found in the xmlSetTreeDoc() function of the libxml2 XML parsing library. This function is responsible for updating document pointers when XML nodes are moved between documents. Due to improper handling of namespace references, a namespace pointer may remain linked to a freed memory region when the original document is destroyed. As a result, subsequent operations that access the namespace can lead to a use-after-free condition, causing an application crash.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libxml2 Debian 14 | 2.15.1+dfsg-0.4 | [DEBIAN-CVE-2025-12863](https://patchblox.com/security/data/fix/linux/debian-cve-2025-12863.md) | Nov 7, 2025 |

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