CVE-2026-44597 Denial of service in Tor

Low 3.7 Published 7 May 2026 Updated 7 May 2026

An out-of-bounds read in Tor allows remote attackers to cause a denial of service via malformed cells lacking reason fields.

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

What is CVE-2026-44597?

CVE-2026-44597 is a low-severity denial of service vulnerability in torproject Tor, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

Tor before 0.4.9.7 has an out-of-bounds read when an END, a TRUNCATE, or a TRUNCATED cell lacks a reason in its payload, aka TROVE-2026-011.

Weakness: CWE-684

Which versions are affected by CVE-2026-44597?

It affects 1 product.

Products include Torproject Tor.

How do I fix CVE-2026-44597?

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-2026-44597 being exploited?

There is no known exploitation of CVE-2026-44597 in the wild and no public exploit code.

Sources

Also known as DEBIAN-CVE-2026-44597, GHSA-94jg-w625-jq92, UBUNTU-CVE-2026-44597.