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rapidyaml through 0.16.0 Out-of-Bounds Write via ParseEngine::_add_annotation()

Affects rapidyaml through 0.16.0 in release builds that parse YAML with three consecutive anchors or tags. The checked facts give no vendor rating and no fixed version.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

6.9MediumCNA
Exploited
No known exploitation
Fix
No fix listed
Who is exposed
Specific setups only

Do first: Check whether your setup matches what the bug needs. Tested version is rapidyaml v0.16.0 Release build with NDEBUG defined, so the capacity assertion is compiled out Input contains three consecutive anchors or tags on one line or across lines

Published
Last modified
Published
Not listed in CISA KEV
17/100 · provisional
Specific setups only
None on Exploit-DB, Metasploit or GitHub

Summary

rapidyaml through 0.16.0 contains an out-of-bounds write vulnerability in ParseEngine::_add_annotation() that allows attackers to corrupt memory by supplying YAML with excess anchors or tags. Attackers can submit YAML with consecutive anchors or tags to overflow the fixed two-element annotation array in release builds, corrupting stack memory and crashing the process.

What to do

  • Check whether your setup matches what the bug needs.

    Tested version is rapidyaml v0.16.0 Release build with NDEBUG defined, so the capacity assertion is compiled out Input contains three consecutive anchors or tags on one line or across lines
  • Workaround: No fix is recorded in the checked facts. Limiting exposure means avoiding untrusted YAML input that contains three consecutive anchors or tags, since the facts document no specific workaround.

Timeline

  1. CVE published
  2. First seen by cve.now

Affected versions

  • biojppm rapidyaml

    through 0.16.0

Evidence 7

  1. Report
  2. Repository
  3. Repository
  4. Repository
  5. Repository
Show all 7 sourcesShow fewer sources
  1. Link
  2. Link

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

FAQ

Questions about CVE-2026-120455

What does this mean?

Parsing YAML with three consecutive anchors or tags on one line writes past the end of a buffer in the parser, overwriting parser control state. Release builds compile out the capacity assertion that would catch this.Source: github.com

Am I affected, and how do I check?

The listed range is rapidyaml version 0 through 0.16.0, tested at v0.16.0 (pinned commit f8ac8dd). The bug needs a release build with NDEBUG defined and input containing three consecutive anchors or tags, such as [&a &b &c x]. The version can be checked in the project's dependency manifest or the vendored rapidyaml source.Source: github.com

What should I do about it?

The checked facts record no fixed version, so no upgrade target can be given. Check the upstream project's release notes or advisory for a patched release.Source: github.com

Is it being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

What if there's no patch?

No fix is recorded in the checked facts. Limiting exposure means avoiding untrusted YAML input that contains three consecutive anchors or tags, since the facts document no specific workaround.Source: github.com