# CVE-2025-15646: libhtml-gumbo-perl: HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion

CVE-2025-15646 is fixed in 4 products on 1 platform, first by DEBIAN-CVE-2025-15646, released June 24, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2025-15646
- Priority: Urgent
- CVSS: 9.8 (critical)
- EPSS: 0.0067
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 1, 2026

## Description

HTML::Gumbo versions before 0.19 for Perl disclose heap memory via type confusion.  Support for the <template> element was added to libgumbo 0.10.0 in 2015, but the walk_tree function in lib/HTML/Gumbo.xs was not updated to support it. The element was treated as a text-node, where strlen() over-reads the heap block that the pointer addresses.  Any caller that runs parse() with the default format => 'string', or with format => 'tree', on input containing a <template> element serializes the over-read bytes into the returned result, disclosing bounded heap contents. format => 'callback' reaches a croak on the unhandled node type and is unaffected.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libhtml-gumbo-perl Debian 12.15 (bookworm) | 0.18-3+deb12u1 | [DEBIAN-CVE-2025-15646](https://patchblox.com/security/data/fix/linux/debian-cve-2025-15646.md) | Jun 24, 2026 |
| Linux | libhtml-gumbo-perl Debian 13.5 (trixie) | 0.18-5 | [DEBIAN-CVE-2025-15646](https://patchblox.com/security/data/fix/linux/debian-cve-2025-15646.md) | Jun 24, 2026 |
| Linux | libhtml-gumbo-perl Debian 14 | 0.18-5 | [DEBIAN-CVE-2025-15646](https://patchblox.com/security/data/fix/linux/debian-cve-2025-15646.md) | Jun 24, 2026 |
| Linux | perl-HTML-Gumbo Fedora 43 | 0.19-1.fc43 | [FEDORA-2026-A457BF78B4](https://patchblox.com/security/data/fix/linux/fedora-2026-a457bf78b4.md) | Jul 2, 2026 |
| Linux | perl-HTML-Gumbo-debuginfo Fedora 43 | 0.19-1.fc43 | [FEDORA-2026-A457BF78B4](https://patchblox.com/security/data/fix/linux/fedora-2026-a457bf78b4.md) | Jul 2, 2026 |
| Linux | perl-HTML-Gumbo-debugsource Fedora 43 | 0.19-1.fc43 | [FEDORA-2026-A457BF78B4](https://patchblox.com/security/data/fix/linux/fedora-2026-a457bf78b4.md) | Jul 2, 2026 |

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Data as of 2026-11-08T19:12:23Z 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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