CVE-2026-75803

CRITICAL CVSS 3.1: 9.1 EPSS 0.22%
Updated Sep 12, 2026
OpenSSL
Parameter Value
CVSS 9.1 (CRITICAL)
Affected Versions 3.0.0 — 4.0.2
Fixed In 3.0.22
Type CWE-354
Vendor OpenSSL
Public PoC No

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.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
None
No disruption

CVSS Vector v3.1

Weakness Type (CWE)

Vulnerable Products 5

Configuration From (including) Up to (excluding)
Openssl Openssl
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
3.0.0 3.0.22
Openssl Openssl
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
3.4.0 3.4.7
Openssl Openssl
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
3.5.0 3.5.8
Openssl Openssl
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
3.6.0 3.6.4
Openssl Openssl
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
4.0.0 4.0.2