Critical 9.1Published Aug 25, 2026

CVE-2026-75803AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()

Updated under an hour ago (2026-10-19 08:00 UTC)

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Exploited in the last 30 days

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.

CVSS: 9.1 CRITICAL (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Weakness (CWE): CWE-354
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: openssl
NVD analysis: Analyzed
Record last updated: Sep 1, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

OpenSSL OpenSSL openssl:openssl (from the name)	from 4.0.0 before 4.0.2; from 3.6.0 before 3.6.4; from 3.5.0 before 3.5.8; from 3.4.0 before 3.4.7; from 3.0.0 before 3.0.22	CNA record
openssl openssl openssl:openssl	from 3.0.0 before 3.0.22; from 3.4.0 before 3.4.7; from 3.5.0 before 3.5.8; from 3.6.0 before 3.6.4; from 4.0.0 before 4.0.2	NVD

References

https://openssl-library.org/news/secadv/20260825.txtvendor-advisory
https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6apatch
https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05bpatch
https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34patch
https://github.com/openssl/openssl/commit/bf95f5f772e9362f87b25cfa2f8cb15d984865b9patch
https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.