CVE-2026-81720 openssl_encrypt before 1.4.9 Denial of Service via Unbounded Argon2

Medium 6.9 Published 27 Aug 2026 Updated 1 Oct 2026

Attackers with local write access can cause a denial of service by crafting identity files with excessive memory costs in the openssl_encrypt library.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2026-81720?

CVE-2026-81720 is a medium-severity denial of service vulnerability in Jahlives Openssl Encrypt, published on 27 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

openssl_encrypt before 1.4.9 fails to validate the memory_cost parameter from identity file protection blocks, allowing attackers to trigger out-of-memory conditions during key derivation. Attackers with write access to local identity stores can craft malicious identity files with excessive memory_cost values that cause the host to crash when unlocking identities before authentication.

Weakness: CWE-400

Which versions are affected by CVE-2026-81720?

1 open source package ship an affected version, including openssl-encrypt. It affects 1 product.

Package	Affected	Fixed in
`openssl-encrypt` PyPI	All versions	`1.4.9`

Products include Jahlives Openssl Encrypt.

How do I fix CVE-2026-81720?

Upgrade openssl-encrypt to 1.4.9 or later.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2026-81720 being exploited?

There is no known exploitation of CVE-2026-81720 in the wild and no public exploit code.

All Jahlives Openssl Encrypt vulnerabilities

Sources

Also known as GHSA-783h-8q2f-f762, GHSA-92rj-569v-9vqg, PYSEC-2026-3965.