libp2p: CPU DoS via oversized IHAVE and IWANT control message arrays
Priority MEDIUM 40CWE-770Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-770.
Summary
libp2p is a JavaScript Implementation of libp2p networking stack. Prior to 16.0.0, @libp2p/gossipsub defaultDecodeRpcLimits set maxIhaveMessageIDs and maxIwantMessageIDs to Infinity, allowing oversized IHAVE and IWANT control message arrays in message/decodeRpc.ts and gossipsub.ts to synchronously iterate roughly 180,000 message IDs per 4 MB frame and block the Node.js event loop. This issue is fixed in version 16.0.0.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0063 50th percentileScored 2026-11-07
Fix Fixed js-libp2p (libp2p): 16.0.0@libp2p/gossipsub (npm): 16.0.0
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| libp2p | js-libp2p | before 16.0.0 | 16.0.0 | Patch available | CNA |
| — | @libp2p/gossipsub (npm) | before 16.0.0 | 16.0.0 | Patch available | GHSA-cwc9-cp4j-mcvv |
- js-libp2p Vendorlibp2p Affected before 16.0.0 Fixed in 16.0.0 Patch available CNA
- @libp2p/gossipsub (npm) Vendor— Affected before 16.0.0 Fixed in 16.0.0 Patch available GHSA-cwc9-cp4j-mcvv
Remediation
- Fix · CNA js-libp2p (libp2p) Fixed in 16.0.0
- Fix · GHSA-cwc9-cp4j-mcvv @libp2p/gossipsub (npm) Fixed in 16.0.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-49866
- 2026-10-03 Alias added: GHSA-cwc9-cp4j-mcvv
- 2026-10-28 EPSS moved to the 50th–90th percentile
References
Other 5
- https://github.com/libp2p/js-libp2p/security/advisories/GHSA-cwc9-cp4j-mcvv
- https://github.com/libp2p/js-libp2p/pull/3520
- https://github.com/libp2p/js-libp2p/commit/773dd80ded24dbd6b19e675c89fd2f3b45f2d899
- https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.0
- https://github.com/libp2p/js-libp2p
More libp2p vulnerabilities
- TI-2026-60386 libp2p-rendezvous through 0.17.1 Denial of Service via Unbounded Registration TTL in Discovery Responses CVSS 4.0HIGH 8.7
- TI-2026-58865 libp2p: PeerStore accepts attacker-signed PeerRecords for a victim peer ID and stores certified attacker addresses CVSS 3.1HIGH 8.2
- TI-2026-44102 libp2p-quic: Remote panic via certificate expiry race during QUIC handshake CVSS 4.0HIGH 8.2
- TI-2026-27587 libp2p-rust has unbounded rendezvous DISCOVER cookies enable remote memory exhaustion CVSS 3.1HIGH 8.2
- TI-2026-58864 libp2p: Gossipsub StrictSign accepts attacker-signed messages as a victim RSA peer ID CVSS 3.1HIGH 7.5
- TI-2026-53982 libp2p: Circuit relay v2 server reservation refresh leaks abort listeners and allows remote resource exhaustion CVSS 3.1HIGH 7.5
Sources
- CVE-2026-49866 · CVE Program
- CVE-2026-49866 · NVD
- FIRST EPSS
- GHSA-cwc9-cp4j-mcvv · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences