CVE-2026-75806 Affecting openssl package, versions <3.6.5-1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published30 Sept 2026
- disclosed29 Sept 2026
Introduced: 29 Sep 2026
NewCVE-2026-75806 (opens in a new tab)How to fix?
Upgrade Debian:unstable openssl to version 3.6.5-1 or higher.
NVD Description
Note: Versions mentioned in the description apply only to the upstream openssl package and not the openssl package as distributed by Debian.
See How to fix? for Debian:unstable relevant fixed versions and status.
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.
References
- https://security-tracker.debian.org/tracker/CVE-2026-75806
- https://github.com/openssl/openssl/commit/04728a289a823e68137f88da016cb9ede307217d
- https://github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972
- https://github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d
- https://github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d
- https://openssl-library.org/news/secadv/20260929.txt