CVE-2026-75803

unknown

Assigned by CNA: openssl

Published 2026-08-25 · Modified 2026-08-25

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

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Description

Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying the supplied authentication tag when the operation is finalized by calling the EVP_Cipher() function. Impact summary: Applications calling EVP_Cipher() on an empty ciphertext and expecting the call to check the AEAD tag may accept forged messages. CWE: CWE-354 (Improper Validation of Integrity Check Value) Description: The EVP_Cipher() API call for AEAD ciphers behaves like a one shot encryption and decryption call. It also verifies the AEAD tag after the decryption operation. However for AES-OCB and ChaCha20-Poly1305 ciphers it skipped the AEAD tag verification when an empty ciphertext was passed to the function. The callers of this function might believe that a successful return indicates a valid AEAD tag for these ciphers, even when that has not truly been validated in this case. FIPS impact: no The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this CVE as the affected algorithms are not FIPS approved and thus not implemented in the FIPS module.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

Mitigation details

Source: Debian Security Tracker · View original ↗ · DFSG

CVE-2026-75803 NameCVE-2026-75803 DescriptionCheck the tag on EVP_Cipher() finalize: Poly1305 and OCB AEADs SourceCVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) Vulnerable and fixed packages The table below lists information on source packages. Source PackageReleaseVersionStatus openssl…

CVE-2026-75803

Name	CVE-2026-75803
Description	Check the tag on EVP_Cipher() finalize: Poly1305 and OCB AEADs
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
openssl (PTS)	bullseye	1.1.1w-0+deb11u1	vulnerable
	bullseye (security)	1.1.1w-0+deb11u8	vulnerable
	bookworm, bookworm (security)	3.0.20-1~deb12u2	vulnerable
	trixie (security), trixie	3.5.6-1~deb13u2	vulnerable
	forky, sid	3.6.3-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
openssl	source	(unstable)	(unfixed)

Notes

https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a (openssl-4.0)
https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b (openssl-3.6)
https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34 (openssl-3.5)
https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42 (openssl-3.0)

Home - Debian Security - Source (Git)

Apply commands

text fix

Notes

https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a (openssl-4.0)https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b (openssl-3.6)https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34 (openssl-3.5)https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42 (openssl-3.0)

OS impact

Debian Affected 5 releases

Version	Status	Fixed in
trixie	Affected	—
sid	Affected	—
forky	Affected	—
bullseye	Affected	—
bookworm	Affected	—

SUSE Affected 1 release

Version	Status	Fixed in
—	Affected	—

References

CWEs

CWE-354

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.