CVE-2026-63374

CRITICALPre-NVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3% (19th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — Patch released this week
9.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 9.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. Prior to 4.14.2, connect_tcp() and TLSStream.wrap() can validate internationalized host names after the standard library converts them with IDNA 2003 instead of IDNA 2008. When a connection to a non-ASCII domain is hijacked or redirected, an attacker can obtain a legitimate certificate for the different ASCII hostname produced by IDNA 2003 and present it to the client, causing the malicious endpoint's certificate to validate. This issue is fixed in version 4.14.2.

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
57
EG Risk 57/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity93% × 45%
Exploitation0% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
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
0.3%
EPSS %ILE
19th
KEV
Not listed

CISA SSVCTrack 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 none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 18, 2026

Last Modified

September 28, 2026

Advisory Details (4)

Auto-updated Oct 3, 2026
Patch available. Sources: github_commit, github_pr, github_release, github.
github Patch Available

TLSStream IDNA 2003 host name encoding enables potential TLS certificate spoofing · Advisory · agronholm/anyio · GitHub

Affected: v4.14.2.

https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6
github_release Patch Available

4.14.2

Patch available: agronholm/anyio 4.14.2

https://github.com/agronholm/anyio/releases/tag/4.14.2
github_pr Patch Available

Fixed TLSStream.wrap() using IDNA 2003 to encode host names

Patch available: agronholm/anyio 4.14.2 (PR #1208 merged 2026-07-08)

https://github.com/agronholm/anyio/pull/1208
github_commit Patch Available

commit 68f58915f82d (agronholm/anyio)

Patch available: agronholm/anyio 4.14.2 (contains commit 68f58915f82d)

https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce

Vendor Advisories for CVE-2026-63374(3)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhaiis/vllm-cuda-rhel9:17906217182026-09-30redhat
redhatrhaiis/vllm-rocm-rhel9:17906217132026-09-30redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
anyio1.0.0 ... 4.9.0 (69 versions)4.14.2—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 38× in last 7d / 48× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

  1. 2026-10-04 09:43 UTCVendor advisory
  2. 2026-10-04 05:58 UTCVendor advisory
  3. 2026-10-04 02:15 UTCVendor advisory
  4. 2026-10-03 22:32 UTCVendor advisory
  5. 2026-10-03 18:48 UTCVendor advisory
  6. 2026-10-03 14:26 UTCEG score recompute
  7. 2026-10-03 14:26 UTCVendor advisory
  8. 2026-10-03 14:26 UTCEPSS rescore
  9. 2026-10-03 10:40 UTCVendor advisory
  10. 2026-10-03 06:57 UTCVendor advisory
  11. 2026-10-03 03:14 UTCVendor advisory
  12. 2026-10-02 23:31 UTCVendor advisory
  13. 2026-10-02 19:46 UTCEG score recompute
  14. 2026-10-02 19:46 UTCVendor advisory
  15. 2026-10-02 17:56 UTCEPSS rescore
  16. 2026-10-02 16:03 UTCVendor advisory
  17. 2026-10-02 12:16 UTCVendor advisory
  18. 2026-10-02 08:19 UTCVendor advisory
  19. 2026-10-02 04:36 UTCVendor advisory
  20. 2026-10-02 00:54 UTCVendor advisory
  21. 2026-10-02 00:53 UTCVendor advisory
  22. 2026-10-01 21:06 UTCEG score recompute
  23. 2026-10-01 21:06 UTCVendor advisory
  24. 2026-10-01 19:50 UTCEPSS rescore
  25. 2026-10-01 17:22 UTCVendor advisory
Show 23 more
  1. 2026-10-01 13:39 UTCVendor advisory
  2. 2026-10-01 09:56 UTCVendor advisory
  3. 2026-10-01 06:13 UTCVendor advisory
  4. 2026-10-01 02:30 UTCVendor advisory
  5. 2026-09-30 15:21 UTCEG score recompute
  6. 2026-09-30 15:03 UTCEPSS rescore
  7. 2026-09-29 16:06 UTCEG score recompute
  8. 2026-09-29 01:12 UTCEG score recompute
  9. 2026-09-28 17:45 UTCEG score recompute
  10. 2026-09-28 16:43 UTCEG score recompute
  11. 2026-09-28 15:36 UTCEG score recompute
  12. 2026-09-28 13:51 UTCEPSS rescore
  13. 2026-09-27 17:17 UTCEG score recompute
  14. 2026-09-26 18:57 UTCEG score recompute
  15. 2026-09-26 15:59 UTCEPSS rescore
  16. 2026-09-26 03:56 UTCEG score recompute
  17. 2026-09-24 14:12 UTCEG score recompute
  18. 2026-09-23 19:09 UTCEG score recompute
  19. 2026-09-23 17:54 UTCEPSS rescore
  20. 2026-09-22 16:23 UTCEG score recompute
  21. 2026-09-22 15:30 UTCEG score recompute▲ 9.30
  22. 2026-09-22 15:29 UTCMITRE cvelistV5CVSS v3 → 9.3 · CVSS v4 → 9.3
  23. 2026-09-18 17:55 UTCEG score recompute

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-63374?
CVE-2026-63374 is a critical vulnerability published on September 18, 2026. AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. Prior to 4.14.2, connect_tcp() and TLSStream.wrap() can validate internationalized host names after the standard library converts them with IDNA 2003 instead of IDNA 2008. When a…
When was CVE-2026-63374 disclosed?
CVE-2026-63374 was first published on September 18, 2026, with the most recent update on September 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63374 actively exploited?
CVE-2026-63374 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (19th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63374?
CVE-2026-63374 has a CVSS base score of 9.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63374?
A fix for CVE-2026-63374 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63374 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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