Is CVE-2026-75803 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-75803 being exploited in the wild.

How severe is CVE-2026-75803?

Critical severity, with a CVSS score of 9.1, published 25 August 2026.

Which products and versions are affected?

OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0 and likely earlier.

Is there a fix for CVE-2026-75803?

A patch was published on 2026-08-19: Patches available via commits 119ab95 and 3621257 on GitHub Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-75803 attacked?

It is attacked over the network.

Am I affected by CVE-2026-75803?

Check whether you run OpenSSL at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-75803: OpenSSL ChaCha20-Poly1305 and AES-OCB authentication tag bypass

CVE-2026-75803 · Severity: critical · CVSS 9.1 · Published 2026-08-25

OpenSSL's encryption library contains a flaw in how it validates authentication tags when decrypting empty messages using ChaCha20-Poly1305 and AES-OCB ciphers. Applications that rely on OpenSSL's EVP_Cipher() function to verify message authenticity may incorrectly accept forged or tampered messages, allowing attackers to bypass cryptographic integrity checks and potentially modify encrypted data without detection.

Technologies: OpenSSL. Vendors: OpenSSL.

Quick answers

Is CVE-2026-75803 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-75803 being exploited in the wild.
How severe is CVE-2026-75803?: Critical severity, with a CVSS score of 9.1, published 25 August 2026.
Which products and versions are affected?: OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0 and likely earlier.
Is there a fix for CVE-2026-75803?: A patch was published on 2026-08-19: Patches available via commits 119ab95 and 3621257 on GitHub Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-75803 attacked?: It is attacked over the network.
Am I affected by CVE-2026-75803?: Check whether you run OpenSSL at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability exists in OpenSSL's EVP_Cipher() API when used with AEAD (Authenticated Encryption with Associated Data) ciphers ChaCha20-Poly1305 and AES-OCB. When an empty ciphertext is passed to EVP_Cipher() for decryption, the function incorrectly returns success without verifying the supplied authentication tag, violating the expected behavior of tag validation. This occurs in the built-in provider's AEAD implementations where the code takes an early exit on empty messages and skips tag comparison. The vulnerability requires only network reachability to an application using affected OpenSSL versions; an attacker can supply a corrupted or forged authentication tag that will be accepted as valid. The fix ensures these ciphers perform tag verification even for empty-ciphertext operations, aligning behavior with the streaming decryption path.

Affected products

OpenSSL OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0 and likely earlier

Timeline

2026-08-25: disclosed
2026-08-19: patched: Patches available via commits 119ab95 and 3621257 on GitHub

References

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