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CVE-2026-81721

7.5 · HIGH

openssl_encrypt before 1.4.9 fails to validate KDF cost parameters in encrypted file metadata and keystore headers, allowing attackers to trigger unbounded memory allocation.

Published Aug 27, 2026CWE-400EPSS 0.58%

Overview

CVE-2026-81721 is a high-severity vulnerability. It was published on August 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

openssl_encrypt before 1.4.9 fails to validate KDF cost parameters in encrypted file metadata and keystore headers, allowing attackers to trigger unbounded memory allocation. Attackers can craft malicious encrypted files declaring arbitrarily large Argon2, scrypt, or balloon KDF parameters to exhaust system memory and crash the process without authentication.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/jahlives/openssl_encrypt/security/advisories/GHSA-7894-5gw8-69hrRefwww.vulncheck.com/advisories/openssl-encrypt-before-1.4.9-denial-of-service-via-kdf-2

How CyberStrike helps

Frequently asked questions

What is CVE-2026-81721?

CVE-2026-81721 is a high-severity vulnerability. It was published on August 27, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-81721?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-81721?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-81721?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-81721 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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