TODDR YAML::Syck up to 1.46 Anchor syck_hdlr_add_anchor anchor name use after free

Summaryinfo

A vulnerability was found in TODDR YAML::Syck up to 1.46. It has been declared as critical. The impacted element is the function syck_hdlr_add_anchor of the component Anchor. Executing a manipulation of the argument anchor name can lead to use after free. This vulnerability is tracked as CVE-2026-57076. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in TODDR YAML::Syck up to 1.46. It has been declared as critical. This vulnerability affects the function syck_hdlr_add_anchor of the component Anchor. The manipulation of the argument anchor name with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at metacpan.org. This vulnerability was named CVE-2026-57076 since 06/23/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 1.47 eliminates this vulnerability.

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Productinfo

Vendor

• TODDR

Name

• YAML::Syck

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18
• 1.19
• 1.20
• 1.21
• 1.22
• 1.23
• 1.24
• 1.25
• 1.26
• 1.27
• 1.28
• 1.29
• 1.30
• 1.31
• 1.32
• 1.33
• 1.34
• 1.35
• 1.36
• 1.37
• 1.38
• 1.39
• 1.40
• 1.41
• 1.42
• 1.43
• 1.44
• 1.45
• 1.46

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