{"id":"CVE-2026-75803","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-75803","summary":"AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()","details":"Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty\nciphertext can report success without verifying the supplied authentication\ntag when the operation is finalized by calling the EVP_Cipher() function.\n\nImpact summary: Applications calling EVP_Cipher() on an empty ciphertext and\nexpecting the call to check the AEAD tag may accept forged messages.\n\nCWE: CWE-354 (Improper Validation of Integrity Check Value)\n\nDescription: The EVP_Cipher() API call for AEAD ciphers behaves like a one\nshot encryption and decryption call. It also verifies the AEAD tag after the\ndecryption operation. However for AES-OCB and ChaCha20-Poly1305 ciphers\nit skipped the AEAD tag verification when an empty ciphertext was passed to\nthe function. The callers of this function might believe that a successful\nreturn indicates a valid AEAD tag for these ciphers, even when that has not\ntruly been validated in this case.\n\nFIPS impact: no\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this CVE\nas the affected algorithms are not FIPS approved and thus not implemented\nin the FIPS module.","published":"2026-08-25T13:00:25.067Z","modified":"2026-09-02T03:47:27.157162564Z","cvss":{"score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[],"fix":{"url":"https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42","label":"openssl/openssl@119ab95"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75803.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-75803"},{"type":"ADVISORY","url":"https://openssl-library.org/news/secadv/20260825.txt"},{"type":"FIX","url":"https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42"},{"type":"FIX","url":"https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b"},{"type":"FIX","url":"https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a"},{"type":"FIX","url":"https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34"},{"type":"FIX","url":"https://github.com/openssl/openssl/commit/bf95f5f772e9362f87b25cfa2f8cb15d984865b9"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-02T03:47:27.157162564Z"}}