CVE-2026-33040: Libp2p gossipsub Gossipsub PRUNE.backoff Duration Overflow Vulnerability

HIGH
Advisory Identifier: GHSA-gc42-3jg7-rxr2
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CWE-190
Published
Advisory Summary

CVE-2026-33040 is a HIGH gossipsub prune.backoff duration overflow vulnerability (CWE-190: Integer Overflow or Wraparound) affecting Libp2p gossipsub libraries in the crates.io ecosystem. The issue involves gossipsub prune.backoff duration overflow. Remediation is available by upgrading affected packages to version 0.49.3.

CVE-2026-33040 at a Glance

CVE Identifier CVE-2026-33040
GHSA Identifier GHSA-gc42-3jg7-rxr2
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-190: Integer Overflow or Wraparound
Affected Product Libp2p gossipsub
Package Ecosystem crates.io
Published Date
Last Updated

How to Fix CVE-2026-33040

To remediate this vulnerability, upgrade all affected Libp2p gossipsub dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

libp2p-gossipsub fixed: 0.49.3 
Upgrade libp2p-gossipsub to 0.49.3
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for libp2p-gossipsub

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-33040, inspect your project dependencies for Libp2p gossipsub:

inspect dependencies for libp2p-gossipsub

Analyze the terminal output to locate any version of Libp2p gossipsub in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.49.3), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-190: Integer Overflow or Wraparound, where the product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. this occurs when an integer value is incremented to a value that is too large to store in the associated representation. when this occurs, the value may become a very small or negative number. In Libp2p gossipsub, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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

CVE-2026-33040 Affected Libp2p gossipsub Versions

1 component(s)
Fixed Versions:
0.49.3
Product / Package Ecosystem Affected Versions Fixed Version
libp2p-gossipsub
 crates.io
< 0.49.3
0.49.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/libp2p/rust-libp2p/security/advisories/GHSA-gc42-3jg7-rxr2
NVD — CVE-2026-33040 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33040
Libp2p gossipsub Source Repository REPOSITORY
https://github.com/libp2p/rust-libp2p

Frequently Asked Questions

What is CVE-2026-33040?
CVE-2026-33040 is a security vulnerability in Libp2p gossipsub involving Gossipsub PRUNE.backoff Duration Overflow under CWE-190: Integer Overflow or Wraparound.
Which Libp2p gossipsub versions are affected?
Affected versions include releases prior to 0.49.3 across affected packages: libp2p-gossipsub.
What version fixes CVE-2026-33040?
Upgrading to 0.49.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is libp2p-gossipsub affected?
Yes, libp2p-gossipsub is affected in releases prior to 0.49.3. Upgrade your dependency to 0.49.3 or later.
What CWE is associated with CVE-2026-33040?
CVE-2026-33040 is classified under CWE-190: Integer Overflow or Wraparound (The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.).
How can I check crates.io dependencies for CVE-2026-33040?
Run the dependency tree command: 'inspect dependencies for libp2p-gossipsub'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gc42-3jg7-rxr2",
  "modified" : "2026-03-20T21:23:14Z",
  "published" : "2026-03-18T19:54:12Z",
  "aliases" : [ "CVE-2026-33040" ],
  "summary" : "Gossipsub PRUNE.backoff Duration Overflow",
  "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",
  "severity" : [ {
    "type" : "CVSS_V4",
    "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "libp2p-gossipsub"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.49.3"
      } ]
    } ]
  } ],
  "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"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-190" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-18T19:54:12Z",
    "nvd_published_at" : "2026-03-20T06:16:12Z"
  }
}