CVE-2026-123611

EUVD-2026-119370
rustls before 0.23.46 contains a key exchange downgrade vulnerability that allows network attackers to poison the per-server-name key-exchange group record via an unauthenticated ServerHello. Attackers can answer one connection with a ServerHello selecting X25519, causing later ClientHellos to send only classical shares and lose post-quantum confidentiality.
Algorithm Downgrade
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
3.7 LOW
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 8.5%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
rustls_projectrustls
𝑥
< 0.23.46
CNA
Debian logo
Debian Releases
Debian Product
Codename
rust-rustls
bookworm
vulnerable
forky
vulnerable
sid
0.23.46+ds-1
fixed
trixie
vulnerable
Common Weakness Enumeration
References
https://github.com/rustls/rustls/security/advisories/GHSA-w44r-93j7-qv28
https://www.vulncheck.com/advisories/rustls-before-0.23.46-key-exchange-downgrade-via-unauthenticated-serverhello