CVE-2026-123613rustls rustls Improper Input Validation
NVD
Vulnerability Summary
Rustls from 0.23.13 before 0.23.45 accepts TLS 1.3 handshake messages at the wrong encryption level when they follow a key-changing message in the same record, because Deframer::aligned does not enforce RFC 8446 record-boundary alignment. A peer or on-path attacker can pack a plaintext EncryptedExtensions with the ServerHello, which rustls accepts unencrypted.
CVSS v4.0 Base Metrics — Score 6.9 (MEDIUM)
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NAttack VectorNetwork
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)Low
Integrity (Vulnerable System)None
Availability (Vulnerable System)None
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
Show CVSS v3.x metrics (score 5.3)
CVSS v3.1 Base Metrics — Score 5.3 (MEDIUM)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NAttack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityLow
IntegrityNone
AvailabilityNone
Affected & Patched Versions
- rustls rustls >= 0.23.13 and < 0.23.45
- rustls rustls 0.23.45
What to do
Fix it during your normal patch cycle. No exploitation is confirmed yet.
- Check whether you run rustls rustls and which version.
- Update to a patched version listed above, then confirm the new version.
Timeline
- Nov 8, 2026Published
- Nov 10, 2026Record last modified
Score, severity and exploitation changes are tracked from the day Watchtower started logging them.
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Data last checked: Nov 14, 2026 02:13 UTC