# CVE-2026-34219: libp2p-gossipsub: Gossipsub PRUNE Backoff Heartbeat Instant Overflow

> A remote attacker can cause a denial of service in the Rust libp2p Gossipsub implementation by sending a crafted PRUNE message that triggers an integer overflow panic.

- **Severity:** High 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 31 Mar 2026
- **Updated:** 31 Mar 2026
- **Also known as:** GHSA-xqmp-fxgv-xvq5

## What is CVE-2026-34219?

CVE-2026-34219 is a high-severity vulnerability in rust-libp2p, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libp2p-rust is the official rust language Implementation of the libp2p networking stack. Prior to version 0.49.4, 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 (backoff_time + 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. This issue has been patched in version 0.49.4.

Weakness: CWE-617 (Reachable Assertion), CWE-190 (Integer Overflow or Wraparound)

## Which versions are affected by CVE-2026-34219?

2 open source packages ship an affected version, including libp2p-gossipsub. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libp2p-gossipsub` | crates.io | All versions | 0.49.4 |
| `libp2p-gossipsub` | crates.io | All versions | 0.49.4 |

Products: Protocol Libp2p-Gossipsub.

## How do I fix CVE-2026-34219?

Upgrade libp2p-gossipsub to 0.49.4 or later.

## Is CVE-2026-34219 being exploited?

There is no known exploitation of CVE-2026-34219 in the wild and no public exploit code.

## Other vulnerabilities in rust-libp2p

- [CVE-2026-33040](https://insights.sbomify.com/CVE-2026-33040/): libp2p-rust: Gossipsub PRUNE.backoff Duration Overflow (high 8.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-34219 and fix it if it is affected.

What it is: CVE-2026-34219 is a high-severity vulnerability in rust-libp2p, published on 31 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-34219 in the wild and no public exploit code.

Affected packages and fixed versions:
- libp2p-gossipsub (crates.io): affected all versions; fixed in 0.49.4
- libp2p-gossipsub (crates.io): affected all versions; fixed in 0.49.4

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-34219/ (Markdown: https://insights.sbomify.com/CVE-2026-34219/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-34219
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-34219
- OSV: https://osv.dev/vulnerability/CVE-2026-34219

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-34219/
Summaries are generated and may contain mistakes; the official description above is the record.