CVE-2026-75806: OpenSSL

Medium severity, CVSS 5.3. EPSS: 0.4% chance of exploitation in the next 30 days.

Issue summary: An established DTLS 1.2 association using an AEAD cipher suite can be terminated by a single unauthenticated datagram whose encrypted fragment is shorter than the mandatory explicit IV and authentication tag overhead. Impact summary: An attacker who can send a datagram that is routed to an existing DTLS 1.2 association can tear that association down without knowing any key material. This is a Denial of Service limited to the targeted association. There is no memory safety or confidentiality impact. CWE: CWE-1284: Improper Validation of Specified Quantity in Input Description: In TLS 1.2 and DTLS 1.2 every record protected by an AEAD cipher suite carries an explicit IV followed by the ciphertext and an authentication tag. When decrypting such a record the record layer passed the record length to the cipher implementation before checking that the record was long enough to contain the explicit IV and the tag. For a record shorter than that overhead the cipher implementation rejected the impossible length, and the record layer treated this as an internal failure and raised a fatal internal_error alert instead of treating the record as one that failed authentication. In TLS 1.2 the same record causes a fatal internal_error alert instead of the expected bad_record_mac alert. Since any undecryptable record already terminates a TLS connection, this is a protocol conformance issue rather than a security issue in TLS. The fix validates the record length against the explicit IV and tag length before any AEAD processing, so that TLS reports bad_record_mac and DTLS silently discards the record. FIPS impact: no The affected code is outside the FIPS module boundary.

Affected products

• OpenSSL OpenSSL: from 1.1.1, before 1.1.1zj (fixed in 1.1.1zj); from 3.0.0, before 3.0.23 (fixed in 3.0.23); from 3.4.0, before 3.4.8 (fixed in 3.4.8); from 3.5.0, before 3.5.9 (fixed in 3.5.9); from 3.6.0, before 3.6.5 (fixed in 3.6.5); from 4.0.0, before 4.0.3 (fixed in 4.0.3)

Published 2026-09-29. Last modified 2026-10-08.