# CVE-2026-120455: rapidyaml through 0.16.0 Out-of-Bounds Write via ParseEngine::_add_annotation()

Status: published. Published: 2026-11-02. Updated: 2026-11-02.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- biojppm / rapidyaml: ≥ 0; ≤ 0.16.0 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/biojppm/rapidyaml/issues/680 (CNA: VulnCheck; issue-tracking)

- https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.def.hpp#L4307-L4351 (CNA: VulnCheck; technical-description)

- https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.def.hpp#L5524-L5535 (CNA: VulnCheck; technical-description)

- https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.hpp#L249-L260 (CNA: VulnCheck; technical-description)

- https://github.com/biojppm/rapidyaml/releases/tag/v0.16.0 (CNA: VulnCheck; release-notes)

- https://hackmd.io/@haindpwn/rapidyaml-parser-annotation-oob-write (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/rapidyaml-through-0.16.0-out-of-bounds-write-via-parseengine-add-annotation (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-120455; retrieved 2026-11-02; source updated 2026-11-02

Revision: e50a82c48ffc9371b0d34eb6ba57f123576df9599a465b3f5c2177e5664cc748

Canonical: https://y2.dev/cve/CVE-2026-120455

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