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

Quick assessment

Affected
OpenSSL OpenSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

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

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I. Basic Information for CVE-2026-75806

Vulnerability Information

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Vulnerability Title
Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
CWE-1284
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
OpenSSL OpenSSL 4.0.0 ~ 4.0.3 -

II. Public POCs for CVE-2026-75806

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III. Intelligence Information for CVE-2026-75806

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Other References for CVE-2026-75806 (5)

Same Patch Batch · OpenSSL · 2026-09-29 · 14 CVEs total

CVE-2026-35189 Excessive Memory Allocation in Relative CRLDP Processing
CVE-2026-35191 QUIC Unvalidated Amplification Credit may be Over Accounted
CVE-2026-75804 QUIC Connection-Level Flow Control is Not Enforced for Streams
CVE-2026-75805 NULL Pointer Dereference in CMP Client Revocation Response Handling
CVE-2026-42772 Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC
CVE-2026-54873 QUIC STREAM Fragment Metadata DoS
CVE-2026-54872 Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves
CVE-2026-54875 Non-Constant-Time SM2 Scalar Multiplication on ARM64 and RISC-V
CVE-2026-77696 Timing Side-Channel in SM2 Signature Generation
CVE-2026-72897 Out-of-Bounds Access After SSL_set_SSL_CTX() During a Handshake
CVE-2026-84782 DTLS Retransmits Handshake Messages From a Stale Buffer Offset
CVE-2026-84784 QUIC: Unbounded RETIRE_CONNECTION_ID Backlog
CVE-2026-84783 Use-After-Free in X.509 Extension Cache Under Concurrent Use

IV. Related Vulnerabilities

Same product: OpenSSL
Same vendor: OpenSSL
Same weakness: CWE-1284

V. Comments for CVE-2026-75806

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