UBUNTU-CVE-2026-26994

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Source
https://ubuntu.com/security/CVE-2026-26994
Import Source
https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26994.json
JSON Data
https://api.osv.dev/v1/vulns/UBUNTU-CVE-2026-26994
Upstream
Published
2026-02-20T03:16:00Z
Modified
2026-02-27T09:59:13Z
Severity
  • 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator
  • Ubuntu - medium
Summary
[none]
Details

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.

References

Affected packages

Ubuntu:22.04:LTS / golang-refraction-networking-utls

Package

Name
golang-refraction-networking-utls
Purl
pkg:deb/ubuntu/golang-refraction-networking-utls@0.0~git20201210.2179f28-1?arch=source&distro=jammy

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

0.*
0.0~git20201210.2179f28-1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "0.0~git20201210.2179f28-1",
            "binary_name": "golang-refraction-networking-utls-dev"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26994.json"

Ubuntu:24.04:LTS / golang-refraction-networking-utls

Package

Name
golang-refraction-networking-utls
Purl
pkg:deb/ubuntu/golang-refraction-networking-utls@1.2.1-2?arch=source&distro=noble

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.2.1-2

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.2.1-2",
            "binary_name": "golang-refraction-networking-utls-dev"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26994.json"

Ubuntu:25.10 / golang-refraction-networking-utls

Package

Name
golang-refraction-networking-utls
Purl
pkg:deb/ubuntu/golang-refraction-networking-utls@1.2.1-3.1?arch=source&distro=questing

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected

Affected versions

1.*
1.2.1-3.1

Ecosystem specific 

{
    "binaries": [
        {
            "binary_version": "1.2.1-3.1",
            "binary_name": "golang-refraction-networking-utls-dev"
        }
    ]
}

Database specific

source 
"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-26994.json"