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Review reviewHigh

CVE-2026-57076

TODDR YAML::Syck

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 r...

CVSS
7.8
EPSS
0.13%
2.95% percentile
CISA KEV
Not listed
Published
2026.07.17
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.13%
Technical severityCVSS 7.8

Vulnerability overview

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 r...

Affected product and versions

Product
TODDR YAML::Syck
Affected versions
< 1.47
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that TODDR YAML::Syck and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416