CVE-2026-63430

MEDIUMPre-NVD 6.36.3
EchelonGraph scoreMEDIUM confidence

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

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (46th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated

Also known asEUVD-2026-102241 (ENISA EUVD) · GHSA-9jh8-v38h-cvhr (GitHub Security Advisories)Source: ENISA EUVD

6.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (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: 0.6%CVSS: 6.3Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

ammonia is a Rust library for repairing and securing untrusted HTML. Prior to 3.3.2, 4.0.2, and 4.1.3, applications that explicitly allow the math tag, annotation-xml, and at least one raw-text HTML element while disallowing the encoding attribute can permit mutation cross-site scripting. ammonia does not correctly implement annotation-xml's encoding-dependent MathML integration-point behavior after attribute filtering removes encoding, so the sanitizer validates a descendant under one namespace interpretation while the browser reparses the output under another. An attacker can use that namespace transition and an allowed raw-text HTML element to execute JavaScript when a user renders the sanitized output. The required tags are not enabled by default, so applications that do not explicitly allow them are not affected. This issue is fixed in versions 3.3.2, 4.0.2, and 4.1.3.

CVSS v3
6.3
EG Score
6.3MEDIUMmedium confidence
EG Risk
59
EG Risk 59/100

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)
Severity63% × 45%
Impact severity (EG Severity): CVSS 6.3 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.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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 at low or medium mission impact and sooner than that at high.
EPSS PROB
0.6%
EPSS %ILE
46th
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 (6.3): severity, escalated by confirmed exploitation. This CVE's 6.3 is its impact severity (EG Severity), not escalated.

EG Severity
6.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). 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; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

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

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

October 15, 2026

Last Modified

October 16, 2026

Advisory Details (10)

Auto-updated Oct 15, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
GitHub release Patch Available

4.1.3

Patch available: rust-ammonia/ammonia v4.1.3

https://github.com/rust-ammonia/ammonia/releases/tag/v4.1.3
GitHub release Patch Available

4.0.2

Patch available: rust-ammonia/ammonia v4.0.2

https://github.com/rust-ammonia/ammonia/releases/tag/v4.0.2
GitHub release Patch Available

3.3.2

Patch available: rust-ammonia/ammonia v3.3.2

https://github.com/rust-ammonia/ammonia/releases/tag/v3.3.2
GitHub commit Patch Available

commit b51bf4f9749e (rust-ammonia/ammonia)

Patch available: rust-ammonia/ammonia v4.1.3 (contains commit b51bf4f9749e)

https://github.com/rust-ammonia/ammonia/commit/b51bf4f9749ed3cd518330105f20a2c39c9ee274
GitHub commit Patch Available

commit 7ac3fd314523 (rust-ammonia/ammonia)

Patch available: rust-ammonia/ammonia v4.0.2 (contains commit 7ac3fd314523)

https://github.com/rust-ammonia/ammonia/commit/7ac3fd3145236f28857eeecbadb544c8659cba31
GitHub commit Patch Available

commit 004bf2cee428 (rust-ammonia/ammonia)

Patch available: rust-ammonia/ammonia v3.3.2 (contains commit 004bf2cee428)

https://github.com/rust-ammonia/ammonia/commit/004bf2cee4288f74a6ee619d589e3e90c24c09ca
GitHub pull request Patch Available

Release 4.1.3 with security fix

Patch available: rust-ammonia/ammonia v4.1.3 (PR #245 merged 2026-06-30)

https://github.com/rust-ammonia/ammonia/pull/245
GitHub pull request Patch Available

Release 4.0.2 with security fix

Patch available: rust-ammonia/ammonia v4.0.2 (PR #244 merged 2026-06-30)

https://github.com/rust-ammonia/ammonia/pull/244
GitHub pull request Patch Available

Release 3.3.2 with security fix

Patch available: rust-ammonia/ammonia v3.3.2 (PR #243 merged 2026-06-30)

https://github.com/rust-ammonia/ammonia/pull/243
GitHub advisoryMentions a patch (unverified)

mXSS in ammonia via MathML `annotation-xml` encoding strip · Advisory · rust-ammonia/ammonia · GitHub

https://github.com/rust-ammonia/ammonia/security/advisories/GHSA-9jh8-v38h-cvhr

Vendor Advisories for CVE-2026-63430(1)

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

Affected Packages

(1 across 1 ecosystem)
crates.io(1)
PackageVulnerable rangeFix by version rangeDependents
ammonia—
  • every version up to 3.3.2: fixed in 3.3.2
  • 4.0.0 up to 4.0.2: fixed in 4.0.2
  • 4.1.0 up to 4.1.3: fixed in 4.1.3
  • 0.0.0-0 up to 3.3.2: fixed in 3.3.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 24× 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 it from the CNA feed. 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). Most recent first.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  2. 2026-10-29 16:41 UTCEG score recompute
  3. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  4. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  5. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  6. 2026-10-26 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  7. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  8. 2026-10-25 14:13 UTCEG score recompute
  9. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  10. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  11. 2026-10-22 19:49 UTCEG score recompute
  12. 2026-10-22 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  13. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  14. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  15. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  16. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  17. 2026-10-18 03:23 UTCEG score recompute
  18. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  19. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  20. 2026-10-15 21:26 UTCEG score recompute
  21. 2026-10-15 20:31 UTCEG score recompute
  22. 2026-10-15 19:35 UTCEG score recompute
  23. 2026-10-15 18:24 UTCEG score recomputeFirst assessed: 6.3 MEDIUM
  24. 2026-10-15 18:22 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63430?
CVE-2026-63430 is a medium-severity vulnerability; its CVE record was published on October 15, 2026. ammonia is a Rust library for repairing and securing untrusted HTML. Prior to 3.3.2, 4.0.2, and 4.1.3, applications that explicitly allow the math tag, annotation-xml, and at least one raw-text HTML element while disallowing the encoding attribute can permit mutation cross-site scripting. ammonia…
When was the CVE record for CVE-2026-63430 published?
The CVE record for CVE-2026-63430 was published on October 15, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 16, 2026; the record at its source may have been updated since.
Is CVE-2026-63430 actively exploited?
CVE-2026-63430 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (46th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63430?
CVE-2026-63430 has a CVSS base score of 6.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63430?
A fix for CVE-2026-63430 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63430 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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