---
id: CVE-2026-75806
title: |-
  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.

  Imp…
summary: |-
  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.

  Imp…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'
cwe:
  - CWE-1284
vendor: OpenSSL
product: OpenSSL
affected:
  - OpenSSL >= 4.0.0 < 4.0.3
  - OpenSSL >= 3.6.0 < 3.6.5
  - OpenSSL >= 3.5.0 < 3.5.9
  - OpenSSL >= 3.4.0 < 3.4.8
  - OpenSSL >= 3.0.0 < 3.0.23
  - OpenSSL >= 1.1.1 < 1.1.1zj
published: '2026-09-29'
updated: '2026-09-29'
sourceUpdated: '2026-09-29T17:17:09.793'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-75806'
references:
  - url: >-
      https://github.com/openssl/openssl/commit/04728a289a823e68137f88da016cb9ede307217d
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d
    label: openssl-security@openssl.org
  - url: >-
      https://github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d
    label: openssl-security@openssl.org
  - url: 'https://openssl-library.org/news/secadv/20260929.txt'
    label: openssl-security@openssl.org
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-29T16:52:47.298458Z'
ingestedAt: '2026-09-29T16:39:33.268Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.