Bug 2543260 (CVE-2026-75806)

Summary:	CVE-2026-75806 openssl: OpenSSL: Denial of Service via undersized DTLS record
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	abarbaro, akhatavk, alizardo, anthomas, aos-team-art-private, asdas, csutherl, dpaolell, ehelms, ggainey, jchui, jclere, jdelft, jhe, jpasqual, jupierce, juwatts, ktsao, lgarciaa, mbiarnes, mdellweg, mhulan, nboldt, nmoumoul, oaljalju, osousa, pcreech, pjindal, plodge, ppalepu, ppostler, prdhamdh, psrna, rchan, rhel-process-autobot, sghai, sidsharm, smallamp, suppawar, szappis, tmalecek, vchlup, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in OpenSSL. A remote, unauthenticated attacker can cause a Denial of Service (DoS) by terminating an active Datagram Transport Layer Security (DTLS) session. By sending an undersized network packet that is shorter than the expected cryptographic overhead, the record processing layer fails to validate the packet length and misinterprets the packet as an internal error rather than an authentication failure. This improper handling triggers a fatal alert that unexpectedly closes the targeted connection without requiring valid encryption keys.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-29 15:54:59 UTC

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.