GHSA-GC42-3JG7-RXR2

Vulnerability from github – Published: 2026-03-18 19:54 – Updated: 2026-03-20 21:23
VLAI?
Summary
Gossipsub PRUNE.backoff Duration Overflow
Details

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 Duration::from_secs(backoff) to Instant::now(), causing overflow and panic.

Impact

Remote unauthenticated denial of service. 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.

Patches

Users should upgrade to a release that hardens Gossipsub backoff handling.

This vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program

Severity ?
8.7 (High)
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
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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "libp2p-gossipsub"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.49.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33040"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-190"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-18T19:54:12Z",
    "nvd_published_at": "2026-03-20T06:16:12Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nThe Rust libp2p Gossipsub implementation accepts attacker-controlled PRUNE backoff values and may perform unchecked time arithmetic when storing backoff state.\nA 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.\n\n### Attack Scenario\nAn attacker that can establish a libp2p Gossipsub session with a target node can crash the target by sending a single crafted PRUNE control message:\n1. Establish a standard libp2p transport session and negotiate a stream multiplexer.\n2. Open a Gossipsub stream and negotiate the meshsub protocol.\n3. Send one protobuf RPC containing ControlPrune with a very large backoff value (e.g. 18446744073709551615 / u64::MAX).\nWhen processed, the oversized backoff can reach time-update logic that adds Duration::from_secs(backoff) to Instant::now(), causing overflow and panic.\n\n### Impact\nRemote unauthenticated denial of service.\nAny 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.\n### Patches\nUsers should upgrade to a release that hardens Gossipsub backoff handling.\n\nThis vulnerability was originally submitted by @revofusion to the Ethereum Foundation bug bounty program",
  "id": "GHSA-gc42-3jg7-rxr2",
  "modified": "2026-03-20T21:23:14Z",
  "published": "2026-03-18T19:54:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/libp2p/rust-libp2p/security/advisories/GHSA-gc42-3jg7-rxr2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33040"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/libp2p/rust-libp2p"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Gossipsub PRUNE.backoff Duration Overflow"
}


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