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Fencer Intel
medium 6.1

CVE-2026-120455 json

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

published 7d ago modified 12h ago also EUVD-2026-115215

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

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.

Patch / fix

Is CVE-2026-120455 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
12h ago

Exploit prediction

0.12% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • hackmd.io https://hackmd.io/@haindpwn/cve-2026-120455-rapidyaml-parser-annotation-oob-write#Detailed-attack-steps referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.9 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
CNA 3.1 6.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
CNA 4.0 6.9 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • biojppm rapidyaml

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.