CVE-2026-75803
AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()
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.
INFO
Published Date :
Aug. 25, 2026, 1:19 p.m.
Last Modified :
Sept. 1, 2026, 7:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
Solution
- Update to a version that validates AEAD tags.
- Ensure empty ciphertexts are validated.
- Review AEAD tag validation logic.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-75803.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-75803 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-75803
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-75803 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-75803 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Sep. 01, 2026
Action Type Old Value New Value Added Reference https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42 Added Reference https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b Added Reference https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a Added Reference https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34 Added Reference https://github.com/openssl/openssl/commit/bf95f5f772e9362f87b25cfa2f8cb15d984865b9 Added Reference https://openssl-library.org/news/secadv/20260825.txt Removed Reference https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42 Removed Reference https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b Removed Reference https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a Removed Reference https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34 Removed Reference https://github.com/openssl/openssl/commit/bf95f5f772e9362f87b25cfa2f8cb15d984865b9 Removed Reference https://openssl-library.org/news/secadv/20260825.txt -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 01, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Added SSVC {'id': 'CVE-2026-75803', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-09-01T18:22:51.167833Z'} -
New CVE Received by [email protected]
Aug. 25, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'OpenSSL', 'product': 'OpenSSL', 'versions': [{'status': 'affected', 'version': '4.0.0', 'lessThan': '4.0.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.6.0', 'lessThan': '3.6.4', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.5.0', 'lessThan': '3.5.8', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.4.0', 'lessThan': '3.4.7', 'versionType': 'semver'}, {'status': 'affected', 'version': '3.0.0', 'lessThan': '3.0.22', 'versionType': 'semver'}], 'defaultStatus': 'unaffected'}] Added 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. Added CWE CWE-354 Added Reference https://github.com/openssl/openssl/commit/119ab9555dc62275bbd71f6f49529b1a44feba42 Added Reference https://github.com/openssl/openssl/commit/3621257986e27e540bf96a11570929a6e5a9e05b Added Reference https://github.com/openssl/openssl/commit/6c7aa6f8f6449b7fe0137ee8be65fcd239bd7d6a Added Reference https://github.com/openssl/openssl/commit/bdeb0cd994d915342787f117ee75044f0dc36f34 Added Reference https://github.com/openssl/openssl/commit/bf95f5f772e9362f87b25cfa2f8cb15d984865b9 Added Reference https://openssl-library.org/news/secadv/20260825.txt