CVE-2026-57077 YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via an unbounded newline scan in newline_len
An out-of-bounds read in YAML::Syck allows attackers to cause denial of service or disclose memory contents by parsing malicious YAML documents.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-57077?
CVE-2026-57077 is a high-severity memory corruption vulnerability in TODDR YAML::Syck, published on 16 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
YAML::Syck versions before 1.47 for Perl allow an out-of-bounds read via an unbounded newline scan in newline_len.
In the bundled libsyck newline_len and is_newline dereference the scan pointer, and the following byte for a "\r\n" pair, with no NUL-terminator or bounds check. During block-scalar lexing at a document boundary the scan runs one byte past the heap lexer buffer. This is an incomplete fix of CVE-2025-11683, on a lexer path the earlier fix did not cover.
Any caller that runs Load or LoadFile on an untrusted document with a block scalar at a document boundary reaches the over-read.
Weakness: CWE-125
Which versions are affected by CVE-2026-57077?
How do I fix CVE-2026-57077?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-57077 being exploited?
There is no known exploitation of CVE-2026-57077 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-57077, AZL-109505, AZL-92907, BELL-CVE-2026-57077, DEBIAN-CVE-2026-57077, GHSA-5wqv-8x52-77q2 and 1 more.