Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS

Summary

CVE	CVE-2026-75806
State	PUBLISHED
Assigner	openssl
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-09-29 16:17:11 UTC
Updated	2026-09-29 21:27:41 UTC
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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from ADP

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

Problem Types: CWE-1284 | CWE-1284 CWE-1284 Improper Validation of Specified Quantity in Input

Version	Source	Type	Score	Severity	Vector
3.1	ADP	DECLARED	5.3	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`
3.1	134c704f-9b21-4f2e-91b3-4a467353bcc0	Secondary	5.3	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

Low

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

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	OpenSSL	OpenSSL	affected 4.0.0 4.0.3 semver	Not specified
CNA	OpenSSL	OpenSSL	affected 3.6.0 3.6.5 semver	Not specified
CNA	OpenSSL	OpenSSL	affected 3.5.0 3.5.9 semver	Not specified
CNA	OpenSSL	OpenSSL	affected 3.4.0 3.4.8 semver	Not specified
CNA	OpenSSL	OpenSSL	affected 3.0.0 3.0.23 semver	Not specified
CNA	OpenSSL	OpenSSL	affected 1.1.1 1.1.1zj custom	Not specified

References

Reference	Source	Link	Tags
github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972	[email protected]	github.com
github.com/openssl/openssl/commit/04728a289a823e68137f88da016cb9ede307217d	[email protected]	github.com
github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d	[email protected]	github.com
openssl-library.org/news/secadv/20260929.txt	[email protected]	openssl-library.org
github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d	[email protected]	github.com
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Mounir Idrassi (en)

There are currently no legacy QID mappings associated with this CVE.