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CVE-2026-75806 — Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS

Affected: OpenSSL

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…

USN-8847-1 — openssl vulnerabilities

Affected: Ubuntu:22.04:LTS: openssl, Ubuntu:24.04:LTS: openssl, Ubuntu:26.04:LTS: openssl

It was discovered that OpenSSL incorrectly handled certain certificate revocation list distribution point names. An attacker could possibly use this issue to cause OpenSSL to consume excessive memory, resulting in a denial of service. (CVE-2026-35189)

It was discovered that OpenSSL incorrectly handled QUIC unvalidated amplification credit accounting. An attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-35191)

It was discovered that OpenSSL incorrectly implemented scalar multiplication for non-NIST elliptic curves. An attacker could possibly use this issue to perform a timing side-channel attack and obtain sensitive information. (CVE-2026-54872)

It was discovered that OpenSSL incorrectly implemented SM2 scalar multiplication on ARM64 and RISC-V architectures. An attacker could possibly use this issue to perform a timing side-channel attack and obtain sensitive information. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-54875)

It was discovered that OpenSSL incorrectly handled SSL context switching during a TLS handshake. An attacker could possibly use this issue to cause an out-of-bounds read, resulting in a denial of service or obtaining sensitive information. This issue only affected Ubuntu 26.04 LTS. (CVE-2026-72897)

It was discovered that OpenSSL incorrectly enforced QUIC connection- level flow control for streams. An attacker could possibly use this issue to cause OpenSSL to consume excess…