CVE-2026-120455

MEDIUMPre-NVD 6.16.1
EchelonGraph scoreHIGH confidence

“—” beside the score: it is equal to the CVSS score beside it.

Score 6.1 from GitHub Security Advisory (severity: MODERATE) published 2026-11-02. A secondary CVSS source baseline 6.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Elevated

Also known asEUVD-2026-115215 (ENISA EUVD) · GHSA-pj6m-mgp5-m3qx (GitHub Security Advisories)Source: ENISA EUVD

6.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 6.1Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
6.1
EG Score
6.1MEDIUMhigh confidence
EG Risk
43
EG Risk 43/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity61% × 45%
Impact severity (EG Severity): CVSS 6.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
1st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (6.1): severity, escalated by confirmed exploitation. This CVE's 6.1 is its impact severity (EG Severity), not escalated.

EG Severity
6.1 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-10). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

November 2, 2026

Last Modified

November 9, 2026

Advisory Details (7)

Auto-updated Nov 2, 2026
Patch available. Sources: github_release.
Web page

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

https://www.vulncheck.com/advisories/rapidyaml-through-0.16.0-out-of-bounds-write-via-parseengine-add-annotation
Web page

rapidyaml: out-of-bounds write in the parser annotation buffer (`_add_annotation`) - HackMD

https://hackmd.io/@haindpwn/rapidyaml-parser-annotation-oob-write
GitHub release Patch Available

Release 0.16.0

Patch available: biojppm/rapidyaml v0.16.0

https://github.com/biojppm/rapidyaml/releases/tag/v0.16.0
Web page

rapidyaml/src/c4/yml/parse_engine.hpp at v0.16.0 · biojppm/rapidyaml · GitHub

https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.hpp#L249-L260
Web page

rapidyaml/src/c4/yml/parse_engine.def.hpp at v0.16.0 · biojppm/rapidyaml · GitHub

https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.def.hpp#L5524-L5535
Web page

rapidyaml/src/c4/yml/parse_engine.def.hpp at v0.16.0 · biojppm/rapidyaml · GitHub

https://github.com/biojppm/rapidyaml/blob/v0.16.0/src/c4/yml/parse_engine.def.hpp#L4307-L4351
Web page

rapidyaml: out-of-bounds write in the parser annotation buffer (`_add_annotation`) · Issue #680 · biojppm/rapidyaml · GitHub

https://github.com/biojppm/rapidyaml/issues/680

Vendor Advisories for CVE-2026-120455(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 18× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

  1. 2026-11-13 16:50 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  2. 2026-11-11 16:38 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  3. 2026-11-11 07:03 UTCEchelonGraph re-scored
  4. 2026-11-11 07:03 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  5. 2026-11-10 16:42 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  6. 2026-11-09 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  7. 2026-11-09 14:41 UTCEchelonGraph re-scored
  8. 2026-11-09 14:41 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  9. 2026-11-09 14:28 UTCEchelonGraph re-scored
  10. 2026-11-09 14:28 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  11. 2026-11-09 14:11 UTCEchelonGraph re-scored
  12. 2026-11-09 14:11 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  13. 2026-11-08 16:38 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  14. 2026-11-07 16:38 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  15. 2026-11-06 16:36 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  16. 2026-11-05 16:36 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  17. 2026-11-04 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  18. 2026-11-04 01:50 UTCEchelonGraph re-scored
  19. 2026-11-04 01:50 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  20. 2026-11-03 16:46 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  21. 2026-11-02 19:28 UTCEchelonGraph re-scored
  22. 2026-11-02 19:28 UTCGHSA enrichmentGHSA-pj6m-mgp5-m3qx · GitHub severity MODERATE · GitHub CVSS 6.1
  23. 2026-11-02 16:03 UTCENISA EUVD ID recordedEUVD-2026-115215 · Source: ENISA EUVD
  24. 2026-11-02 15:26 UTCEchelonGraph re-scored
  25. 2026-11-02 14:32 UTCEchelonGraph re-scoredFirst assessed: 6.1 MEDIUM
Show 1 more
  1. 2026-11-02 14:32 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-120455?
CVE-2026-120455 is a medium-severity vulnerability; its CVE record was published on November 2, 2026. 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…
When was CVE-2026-120455 made public?
CVE-2026-120455 was made public on November 1, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on November 2, 2026. EchelonGraph's copy of the record carries a last-modified date of November 9, 2026; the record at its source may have been updated since.
Is CVE-2026-120455 actively exploited?
CVE-2026-120455 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (1st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-120455?
CVE-2026-120455 has a CVSS base score of 6.1 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-120455?
A fix for CVE-2026-120455 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-120455 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-120455

Explore →

Is Your Infrastructure Affected by CVE-2026-120455?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.