CVE-2026-26994
uTLS ServerHellos are accepted without checking TLS 1.3 downgrade canaries
02 Description
uTLS ServerHellos are accepted without checking TLS 1.3 downgrade canaries
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 0.30% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 22.6% of scored records. A rank, not a probability.
- NVD base score
- 6.5 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- NVD analysis status
- Analyzed. NVD last modified this record on 2026-06-17.
- Red Hat severity
- No Red Hat rating. Red Hat rates the CVEs that affect its products.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2026-02-20 02:50Z8 MO AGO
- Last updated
- 2026-02-20 15:12Z8 MO AGO
- Reserved
- 2026-02-17
- Assigning CNA
- GitHub_M
- Record state
- PUBLISHED
- Severity
- Medium (CVSS 6.5)
- CNA CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- Weaknesses
- CWE-693Protection Mechanism FailurePillar
- Data version
- 5.2
- Document digest
- 53f5bf5f4e788125de7dea0364bcc3769172354f7feed7dc5c903af81813e889
05 Affected products
06 References
- github.comhttps://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96
- github.comhttps://github.com/refraction-networking/utls/issues/181
- github.comhttps://github.com/refraction-networking/utls/pull/337
- github.comhttps://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9
07 Fixed in
Debian 12
- golang-refraction-networking-utls No fix yet
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- golang-refraction-networking-utls No fix yet
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- golang-refraction-networking-utls No fix yet
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 22.04 LTS
- golang-refraction-networking-utls No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 24.04 LTS
- golang-refraction-networking-utls No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 25.10
- golang-refraction-networking-utls No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.04 LTS
- golang-refraction-networking-utls No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
Ubuntu 26.10
- golang-refraction-networking-utls No fix yet
Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.