CVE-2026-81721: openssl_encrypt before 1.4.9 Denial of Service via KDF

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-27 · updated 2026-09-02
Weakness: CWE-400

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.

Affected products

jahlives openssl_encrypt: before 1.4.9 — fixed in 1.4.9

How to fix

Upgrade to a fixed version: jahlives openssl_encrypt 1.4.9. Check the vendor advisory for mitigations.

References

https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-7894-5gw8-69hr
https://www.vulncheck.com/advisories/openssl-encrypt-before-1.4.9-denial-of-service-via-kdf-2

Get alerted when CVE-2026-81721 or the next vulnerability affects your stack