# CVE-2026-95859: libp2p-rust: Gossipsub GRAFT topics unbounded growth

> Remote attackers can cause memory exhaustion and denial of service in libp2p-rust by sending unbounded GRAFT topics.

- **Severity:** High 8.7 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Oct 2026
- **Updated:** 21 Oct 2026
- **Also known as:** GHSA-g3g5-x568-qvqx

## What is CVE-2026-95859?

CVE-2026-95859 is a high-severity denial of service vulnerability in rust-libp2p, published on 16 Oct 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 0.49.5, Gossipsub GRAFT control-message handling unconditionally adds attacker-supplied topic hashes to connected_peer.topics without confirming that the peer previously subscribed to those topics. A remote unauthenticated peer that can reach a Gossipsub listener can repeatedly send novel GRAFT topics, causing cumulative per-peer memory growth that is not bounded by subscription filters, peer scoring, or per-message size limits. This can exhaust process memory and cause a denial of service. This issue is fixed in version 0.49.5.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-95859?


## How do I fix CVE-2026-95859?

No fix has been published for CVE-2026-95859 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-95859 being exploited?

There is no known exploitation of CVE-2026-95859 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-95859 and fix it if it is affected.

What it is: CVE-2026-95859 is a high-severity denial of service vulnerability in rust-libp2p, published on 16 Oct 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-2026-95859 in the wild and no public exploit code.

Affected product: rust-libp2p. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-95859/ (Markdown: https://insights.sbomify.com/CVE-2026-95859/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-95859
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-95859
- OSV: https://osv.dev/vulnerability/CVE-2026-95859

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-95859/
Summaries are generated and may contain mistakes; the official description above is the record.