CVE-2026-33040 libp2p-rust: Gossipsub PRUNE.backoff Duration Overflow

What is CVE-2026-33040?

CVE-2026-33040 is a high-severity vulnerability in rust-libp2p, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

libp2p-rust is the official rust language Implementation of the libp2p networking stack. In versions prior to 0.49.3, the Gossipsub implementation accepts attacker-controlled PRUNE backoff values and may perform unchecked time arithmetic when storing backoff state. A specially crafted PRUNE control message with an extremely large backoff (e.g. u64::MAX) can lead to Duration/Instant overflow during backoff update logic, triggering a panic in the networking state machine. This is remotely reachable over a normal libp2p connection and does not require authentication. Any application exposing a libp2p Gossipsub listener and using the affected backoff-handling path can be crashed by a network attacker that can reach the service port. The attack can be repeated by reconnecting and replaying the crafted control message. This issue has been fixed in version 0.49.3.

Weakness: CWE-190

Which versions are affected by CVE-2026-33040?

2 open source packages ship an affected version, including libp2p-gossipsub. It affects 1 product.

Products include Protocol Libp2p-Gossipsub.

How do I fix CVE-2026-33040?

Upgrade libp2p-gossipsub to 0.49.3 or later.

Is CVE-2026-33040 being exploited?

There is no known exploitation of CVE-2026-33040 in the wild and no public exploit code.

Other vulnerabilities in rust-libp2p

• CVE-2026-34219 libp2p-gossipsub: Gossipsub PRUNE Backoff Heartbeat Instant Overflow High 8.2

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as GHSA-gc42-3jg7-rxr2, UBUNTU-CVE-2026-33040.