CVE-2026-57077 TODDR CVE debrief

Who should care

Users of YAML::Syck versions before 1.47 for Perl should be aware of this vulnerability and take steps to mitigate it. This includes updating to version 1.47 or later, and being cautious when loading untrusted documents. The vulnerability can be exploited by loading an untrusted document with a block scalar at a document boundary, which can lead to an out-of-bounds read.

Technical summary

The vulnerability is caused by the lack of a bounds check in the newline_len function, which can lead to an out-of-bounds read. The is_newline function also dereferences the scan pointer and the following byte for a 'r' 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. The vulnerability affects YAML::Syck versions before 1.47 for Perl.

Defensive priority

High

Recommended defensive actions

• Update YAML::Syck to version 1.47 or later
• Be cautious when loading untrusted documents
• Implement bounds checking when loading documents
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record was published on 2026-07-16T22:17:43.650Z and has not been modified since then. The NVD entry is currently Received. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the vendor. The vulnerability affects YAML::Syck versions before 1.47 for Perl. The CVE record does not provide additional details about the vulnerability, and defenders should review the official advisory or CVE record for more information.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.