libp2p-gossipsub: Remote crash via unchecked Instant overflow in heartbeat backoff expiry handling

Exploitation

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

CVSS 4.0

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

EPSS

• CVE-2026-34219: 0.58% estimated exploitation activity in the next 30 days; percentile 47.92 (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.

Description Summary The Rust libp2p Gossipsub implementation contains a remotely reachable panic in backoff expiry handling. After a peer sends a crafted PRUNE control message with an attacker-controlled, near-maximum backoff value, the value is accepted and stored as an Instant near the representable upper bound. On a later heartbeat, the implementation performs unchecked Instant + Duration arithmetic (backofftime + slack), which can overflow and panic with: overflow when adding duration to instant This issue is reachable from any Gossipsub peer over normal TCP + Noise + mplex/yamux connectivity and requires no further authentication beyond becoming a protocol peer. Attack Scenario An attacker that can establish a libp2p Gossipsub session with a target node can crash the target by sending crafted PRUNE control data: 1. Establish a standard libp2p session (TCP + Noise) and negotiate a stream multiplexer (mplex/yamux). 2. Open a Gossipsub stream and send an RPC containing ControlPrune…

Published by the source

30 Mar 2026, 13:04 UTC

Last modified by the source

6 Apr 2026, 23:13 UTC

Source last checked

26 Oct 2026, 15:42 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-xqmp-fxgv-xvq5

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

# Patch Next advisory brief: CVE-2026-34219

Advisory: libp2p-gossipsub: Remote crash via unchecked Instant overflow in heartbeat backoff expiry handling
IDs: CVE-2026-34219, GHSA-xqmp-fxgv-xvq5
Record: https://patchnext.com/advisories/cve-2026-34219 (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 8.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: libp2p-gossipsub 0.49.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io libp2p-gossipsub: affected < 0.49.4; fixed in 0.49.4

## 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-xqmp-fxgv-xvq5 (GitHub-reviewed advisory GHSA-xqmp-fxgv-xvq5 lists affected ranges: crates.io libp2p-gossipsub >=0 <0.49.4)

Commands are suggestions: review each one before running it.