CVE-2026-35457 — libp2p-rendezvous
HIGHCVE-2026-35457 is a high-severity (CVSS 8.2) CWE-770 vulnerability in libp2p-rendezvous. A fix is available for libp2p-rendezvous — see the affected versions and patch details below.
libp2p-rendezvous: Unbounded rendezvous DISCOVER cookies enable remote memory exhaustion
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-35457.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-35457 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
libp2p-rendezvousReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The rendezvous server stores pagination cookies without bounds. An unauthenticated peer can repeatedly issue DISCOVER requests and force unbounded memory growth.
Details
Pagination state is stored in:
HashMap<Cookie, HashSet<RegistrationId>>
On Message::Discover:
remote peer
→ DISCOVER
→ handle_request
→ registrations.get(...)
→ new cookie generated
→ cookie inserted into Registrations::cookies
There is no upper bound or eviction policy, so repeated DISCOVER requests grow this map indefinitely.
PoC
A reproduction test and minimal harness will be provided in a private fork in a follow-up comment.
Impact
Remote state amplification leading to memory exhaustion.
Properties:
- etwork reachable
- no authentication required
- low attack complexity
- protocol-compliant traffic
Impacts rendezvous nodes exposed to untrusted peers.
Possible Fixes
- Global cap + eviction
Bound cookie storage (MAX_COOKIES_TRACKED) with FIFO/expiry aware eviction.
Tradeoff: attacker can churn cookies and evict legitimate pagination state.
- Stateless cookies
Encode pagination state in authenticated cookies instead of storing server-side state.
Tradeoff: more complex implementation.
- Rate limiting / per-peer quotas
Limit cookie creation per peer.
Tradeoff: requires peer tracking.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | libp2p-rendezvous | all versions | 0.17.1cargo update -p libp2p-rendezvous --precise 0.17.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for libp2p-rendezvous, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update libp2p-rendezvous to 0.17.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-35457 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-35457 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-35457. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-35457 in your dependencies?
O3 Security finds CVE-2026-35457 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.