CVE-2026-123613 PUBLISHED

Rustls 0.23.13 before 0.23.45 TLS 1.3 Handshake Encryption Level Bypass

Assigner: VulnCheck
Reserved: 06.11.2026 Published: 08.11.2026 Updated: 08.11.2026

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 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS Score: 6.9

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	Low	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS Score: 5.3

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	None	Integrity Impact	None
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	rustls
Product	rustls
Versions	Default: unaffected affected from 0.23.13 to 0.23.45 (excl.) Version 0.23.45 is unaffected

CVE-2026-123613 PUBLISHED

Rustls 0.23.13 before 0.23.45 TLS 1.3 Handshake Encryption Level Bypass

Metrics

Product Status

Credits

References

Problem Types