# CVE-2026-57076: libyaml-syck-perl: YAML::Syck versions before 1.47 for Perl allow a heap use-after-free via an anchor name reused as an anchors-table ke...

CVE-2026-57076 is fixed in 5 products on 1 platform, first by FEDORA-2026-C8484F1AFB, released July 14, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-57076
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 14, 2026

## Description

YAML::Syck versions before 1.47 for Perl allow a heap use-after-free via an anchor name reused as an anchors-table key in syck_hdlr_add_anchor.  In the bundled libsyck an anchor name allocated by syck_strndup is stored both as node->anchor, freed when the node is freed, and as the key in the parser's anchors table. Freeing the node frees the shared key, and a later anchor redefinition makes st_delete compare against the freed key, so st_strcmp reads freed heap memory. Anchors are a standard YAML feature and need no special flags, so this is reached on the default Load path.  Any caller that runs Load or LoadFile on an untrusted document that redefines an anchor reaches the read of freed memory.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libyaml-syck-perl Debian 12.15 (bookworm) | 1.34-2+deb12u3 | [DEBIAN-CVE-2026-57076](https://patchblox.com/security/data/fix/linux/debian-cve-2026-57076.md) | Jul 19, 2026 |
| Linux | libyaml-syck-perl Debian 13.5 (trixie) | 1.34-2+deb13u3 | [DEBIAN-CVE-2026-57076](https://patchblox.com/security/data/fix/linux/debian-cve-2026-57076.md) | Jul 19, 2026 |
| Linux | libyaml-syck-perl Debian 14 | 1.47-1 | [DEBIAN-CVE-2026-57076](https://patchblox.com/security/data/fix/linux/debian-cve-2026-57076.md) | Jul 19, 2026 |
| Linux | perl-YAML-Syck Fedora 43 | 1.47-1.fc43 | [FEDORA-2026-C8484F1AFB](https://patchblox.com/security/data/fix/linux/fedora-2026-c8484f1afb.md) | Jul 14, 2026 |
| Linux | perl-YAML-Syck amzn 2023 | 1.37-1.amzn2023.0.4 | [ALAS2023-2026-2007](https://patchblox.com/security/data/fix/linux/alas2023-2026-2007.md) | Aug 3, 2026 |
| Linux | perl-YAML-Syck opensuse-leap 16.0 | 1.470.0-bp160.1.1 | [OPENSUSE-SU-2026:21497-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21497-1.md) | Jul 29, 2026 |
| Linux | perl-YAML-Syck-debuginfo Fedora 43 | 1.47-1.fc43 | [FEDORA-2026-C8484F1AFB](https://patchblox.com/security/data/fix/linux/fedora-2026-c8484f1afb.md) | Jul 14, 2026 |
| Linux | perl-YAML-Syck-debuginfo amzn 2023 | 1.37-1.amzn2023.0.4 | [ALAS2023-2026-2007](https://patchblox.com/security/data/fix/linux/alas2023-2026-2007.md) | Aug 3, 2026 |
| Linux | perl-YAML-Syck-debugsource Fedora 43 | 1.47-1.fc43 | [FEDORA-2026-C8484F1AFB](https://patchblox.com/security/data/fix/linux/fedora-2026-c8484f1afb.md) | Jul 14, 2026 |
| Linux | perl-YAML-Syck-debugsource amzn 2023 | 1.37-1.amzn2023.0.4 | [ALAS2023-2026-2007](https://patchblox.com/security/data/fix/linux/alas2023-2026-2007.md) | Aug 3, 2026 |
| Linux | perl-YAML-Syck-tests amzn 2023 | 1.37-1.amzn2023.0.4 | [ALAS2023-2026-2007](https://patchblox.com/security/data/fix/linux/alas2023-2026-2007.md) | Aug 3, 2026 |

---

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

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.