CVE-2026-26994

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 81% of all CVEs by exploit prediction. 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
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0.

CVSS v3
6.5
EG Score
6.5(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: Track

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
Severity65% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
19%
KEV
Not listed

Published

February 20, 2026

Last Modified

June 17, 2026

Advisory Details (4)

Auto-updated Aug 6, 2026
Patch available. Sources: github_commit, github_pr, github.
github Patch Available

ServerHellos are accepted without checking TLS 1.3 downgrade canaries · Advisory · refraction-networking/utls · GitHub

https://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96
github_pr Patch Available

Fix check for TLS downgrade canary

Patch available: refraction-networking/utls v1.7.0 (PR #337 merged 2025-04-20)

https://github.com/refraction-networking/utls/pull/337
generic

Tls downgrade attack? · Issue #181 · refraction-networking/utls · GitHub

https://github.com/refraction-networking/utls/issues/181
github_commit Patch Available

commit f8892761e2a4 (refraction-networking/utls)

Patch available: refraction-networking/utls v1.7.0 (contains commit f8892761e2a4)

https://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
golang-refraction-networking-utls0.0~git20201210.2179f28-1, 1.2.1-1, 1.2.1-2, 1.2.1-3, 1.2.1-3.1——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
golang-refraction-networking-utls1.2.1-2, 1.2.1-3, 1.2.1-3.1——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
golang-refraction-networking-utls1.2.1-3.1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
golang-refraction-networking-utls1.2.1-3.1——
Go(1)
PackageVulnerable rangeFixed inDependents
github.com/refraction-networking/utls—1.7.0—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 28× 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. 2026-09-18 20:36 UTCOSV refresh
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 19:27 UTCEPSS rescore
  4. 2026-09-17 19:30 UTCEPSS rescore
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-13 16:47 UTCEPSS rescore
  8. 2026-09-12 15:01 UTCEPSS rescore
  9. 2026-09-11 14:52 UTCEPSS rescore
  10. 2026-09-10 09:34 UTCEPSS rescore
  11. 2026-09-08 22:00 UTCEPSS rescore
  12. 2026-09-07 16:01 UTCEPSS rescore
  13. 2026-09-06 13:47 UTCEPSS rescore
  14. 2026-09-06 13:47 UTCEPSS rescore
  15. 2026-09-04 05:06 UTCEPSS rescore
  16. 2026-09-02 14:11 UTCEPSS rescore
  17. 2026-09-01 13:53 UTCEPSS rescore
  18. 2026-09-01 04:39 UTCEPSS rescore
  19. 2026-08-30 23:23 UTCOSV refresh
  20. 2026-08-30 19:17 UTCEPSS rescore
  21. 2026-08-30 01:22 UTCEPSS rescore
  22. 2026-08-28 21:41 UTCEPSS rescore
  23. 2026-08-27 14:25 UTCEPSS rescore
  24. 2026-08-26 14:46 UTCEPSS rescore
  25. 2026-08-25 13:48 UTCEPSS rescore
Show 32 more
  1. 2026-08-23 00:19 UTCEPSS rescore
  2. 2026-08-21 23:49 UTCEPSS rescore
  3. 2026-08-20 22:55 UTCEPSS rescore
  4. 2026-08-19 17:03 UTCEPSS rescore
  5. 2026-08-18 13:48 UTCEPSS rescore
  6. 2026-08-17 13:47 UTCEPSS rescore
  7. 2026-08-16 14:56 UTCEPSS rescore
  8. 2026-08-16 02:14 UTCEPSS rescore
  9. 2026-08-15 01:30 UTCEPSS rescore
  10. 2026-08-14 09:30 UTCEG score recompute
  11. 2026-08-13 22:00 UTCEPSS rescore
  12. 2026-08-13 02:23 UTCEG score recompute
  13. 2026-08-12 13:50 UTCEPSS rescore
  14. 2026-08-12 01:55 UTCEG score recompute
  15. 2026-08-11 13:42 UTCEPSS rescore
  16. 2026-08-11 00:00 UTCEPSS rescore
  17. 2026-08-10 09:35 UTCEG score recompute
  18. 2026-08-09 13:46 UTCEPSS rescore
  19. 2026-08-09 09:06 UTCEG score recompute
  20. 2026-08-08 16:37 UTCEPSS rescore
  21. 2026-08-07 21:20 UTCEG score recompute
  22. 2026-08-06 13:46 UTCEPSS rescore
  23. 2026-08-06 03:22 UTCEG score recompute
  24. 2026-08-05 19:17 UTCEPSS rescore
  25. 2026-08-04 15:10 UTCEPSS rescore
  26. 2026-08-03 10:36 UTCEPSS rescore
  27. 2026-08-02 20:03 UTCEG score recompute
  28. 2026-08-01 04:16 UTCEPSS rescore
  29. 2026-07-30 16:27 UTCEPSS rescore
  30. 2026-07-30 01:30 UTCEPSS rescore
  31. 2026-07-28 15:36 UTCEPSS rescore
  32. 2026-07-27 14:13 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-26994?
CVE-2026-26994 is a medium vulnerability published on February 20, 2026. uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec.…
When was CVE-2026-26994 disclosed?
CVE-2026-26994 was first published in the National Vulnerability Database on February 20, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26994 actively exploited?
CVE-2026-26994 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 80.8% of all scored CVEs.
What is the CVSS score of CVE-2026-26994?
CVE-2026-26994 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-26994?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-26994, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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