{"id":"CVE-2026-35457","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-35457","summary":"libp2p-rendezvous: Unbounded rendezvous DISCOVER cookies enable remote memory exhaustion","details":"### Summary\nThe rendezvous server stores pagination cookies without bounds. An unauthenticated peer can repeatedly issue `DISCOVER` requests and force unbounded memory growth.\n\n### Details\n\nPagination state is stored in:\n\n```rs\nHashMap<Cookie, HashSet<RegistrationId>>\n```\n\nOn `Message::Discover`:\n\n```\nremote peer\n→ DISCOVER\n→ handle_request\n→ registrations.get(...)\n→ new cookie generated\n→ cookie inserted into Registrations::cookies\n```\n\nThere is **no upper bound or eviction policy**, so repeated DISCOVER requests grow this map indefinitely.\n\n\n### PoC\nA reproduction test and minimal harness will be provided in a private fork in a follow-up comment.\n\n### Impact\n\n**Remote state amplification leading to memory exhaustion.**\n\n\nProperties:\n\n- etwork reachable\n- no authentication required\n- low attack complexity\n- protocol-compliant traffic\n\nImpacts rendezvous nodes exposed to untrusted peers.\n---\n\n### Possible Fixes\n\n1. **Global cap + eviction**\n\nBound cookie storage (`MAX_COOKIES_TRACKED`) with FIFO/expiry aware eviction.  \nTradeoff: attacker can churn cookies and evict legitimate pagination state.\n\n2. **Stateless cookies**\n\nEncode pagination state in authenticated cookies instead of storing server-side state.  \nTradeoff: more complex implementation.\n\n3. **Rate limiting / per-peer quotas**\n\nLimit cookie creation per peer.  \nTradeoff: requires peer tracking.","published":"2026-04-04T06:34:29Z","modified":"2026-04-07T20:21:43.969674Z","cvss":{"score":8.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"libp2p-rendezvous","fixedVersion":"0.17.1"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/libp2p/rust-libp2p/security/advisories/GHSA-v5hw-cv9c-rpg7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-35457"},{"type":"PACKAGE","url":"https://github.com/libp2p/rust-libp2p"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-04-07T20:21:43.969674Z"}}