CVE-2026-48852 Denial of service in PuTTY

Low 3.7 Published 25 May 2026 Updated 26 May 2026

An attacker can cause a denial of service in PuTTY via an assertion failure during ECDSA signature verification.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2026-48852?

CVE-2026-48852 is a low-severity denial of service vulnerability in PuTTY, published on 25 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

PuTTY 0.71 before 0.84 has an assertion failure in ECDSA signature verification.

Weakness: CWE-617

Which versions are affected by CVE-2026-48852?

It affects 1 product.

Products include Putty Putty.

How do I fix CVE-2026-48852?

Upgrade to a fixed version.

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-2026-48852 being exploited?

There is no known exploitation of CVE-2026-48852 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-48852, GHSA-rx8r-f2xx-98h9, UBUNTU-CVE-2026-48852.