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.
CVE-2026-26994
This medium-severity CVE scores 6.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.5
- EG Score
- 6.5(low)
- 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 computedSeverity65% × 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
References (4)
- security-advisories@githubhttps://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9
- security-advisories@githubhttps://github.com/refraction-networking/utls/issues/181
- security-advisories@githubhttps://github.com/refraction-networking/utls/pull/337
- security-advisories@githubhttps://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 1× in last 7d / 1× 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.
- 2026-07-27 14:13 UTCEG score recompute
Related CVEs(same CWE)
Same CWE
10 shownCWE-693
- CVE-2021-32835EG 9.9EPSS p91CRITICAL
- CVE-2019-10328EG 9.9CRITICAL
- CVE-2019-1003030EG 9.9 KEVEPSS p99CRITICAL
- CVE-2021-27497NVD 6.5EG 9.8CRITICAL
- CVE-2020-10887EG 9.8EPSS p90CRITICAL
- CVE-2017-3197EG 9.8EPSS p92CRITICAL
- CVE-2018-9318EG 9.8EPSS p90CRITICAL
- CVE-2018-9311EG 9.8EPSS p90CRITICAL
- CVE-2017-8864EG 9.8CRITICAL
- CVE-2013-2465EG 9.8 KEVEPSS p100CRITICAL
Frequently asked(5)
What is CVE-2026-26994?
When was CVE-2026-26994 disclosed?
Is CVE-2026-26994 actively exploited?
What is the CVSS score of CVE-2026-26994?
How do I remediate CVE-2026-26994?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-26994
Is Your Infrastructure Affected by CVE-2026-26994?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.