Gossipsub PRUNE.backoff Duration Overflow

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

8.7 · CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N · score source

EPSS

• CVE-2026-33040: 0.59% estimated exploitation activity in the next 30 days; percentile 48.20 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The Rust libp2p 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. Attack Scenario An attacker that can establish a libp2p Gossipsub session with a target node can crash the target by sending a single crafted PRUNE control message: 1. Establish a standard libp2p transport session and negotiate a stream multiplexer. 2. Open a Gossipsub stream and negotiate the meshsub protocol. 3. Send one protobuf RPC containing ControlPrune with a very large backoff value (e.g. 18446744073709551615 / u64::MAX). When processed, the oversized backoff can reach time-update logic that adds…

Published by the source

18 Mar 2026, 19:54 UTC

Last modified by the source

20 Mar 2026, 21:23 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-gc42-3jg7-rxr2

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-33040

Advisory: Gossipsub PRUNE.backoff Duration Overflow
IDs: CVE-2026-33040, GHSA-gc42-3jg7-rxr2
Record: https://patchnext.com/advisories/cve-2026-33040 (revision 1, source checked 26 Oct 2026, 15:42 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: libp2p-gossipsub 0.49.3. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io libp2p-gossipsub: affected < 0.49.3; fixed in 0.49.3

## Suggested inspection (read-only)
- crates.io libp2p-gossipsub: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on libp2p-gossipsub.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-gc42-3jg7-rxr2 (GitHub-reviewed advisory GHSA-gc42-3jg7-rxr2 lists affected ranges: crates.io libp2p-gossipsub >=0 <0.49.3)

Commands are suggestions: review each one before running it.