Memory corruption via fixed-size emitter tag buffer
Published Mar 16, 2026 · Updated Mar 16, 2026
Multiple memory-safety flaws in YAML::Syck 1.36 and earlier allow remote attackers to read memory, corrupt data, or crash Perl processes. The emitter appends class names to a fixed 512-byte heap buffer without resizing it; separate decoder, parser, and anchor paths overread input, mutate shared type data, or leak an anchor. Reachability depends on a consuming application passing attacker-influenced YAML or class names into the affected Load or Dump paths.
Summary
What happened
Multiple memory-safety flaws in YAML::Syck 1.36 and earlier allow remote attackers to read memory, corrupt data, or crash Perl processes. The emitter appends class names to a fixed 512-byte heap buffer without resizing it; separate decoder, parser, and anchor paths overread input, mutate shared type data, or leak an anchor. Reachability depends on a consuming application passing attacker-influenced YAML or class names into the affected Load or Dump paths.
The record
- CVE
- CVE-2026-4177
- Published
- Mar 16, 2026
- Updated
- Mar 16, 2026
- Vendor
- Todd Rinaldo
- Product
- YAML::Syck
- Classifications
- CWE-120, CWE-122
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 16, 2026CVE publishedPublication date reported by the CVE source.
- Mar 16, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=1.36
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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