JavaScript Network Stack Vulnerability in libp2p by Protocol Labs
CVE-2026-49866

7.5HIGH

Key Information:

Vendor

Libp2p

Status
Js-libp2p
Vendor
CVE Published:
8 July 2026

What is CVE-2026-49866?

The libp2p networking stack, a JavaScript implementation, contains a significant vulnerability prior to version 16.0.0. Specifically, the default settings for @libp2p/gossipsub's decode RPC limits allow for an unlimited number of oversized IHAVE and IWANT control message arrays. This issue can lead to a synchronously iterated processing of roughly 180,000 message IDs in a single 4 MB frame, which may block the Node.js event loop, severely impacting the application's performance. Users are advised to upgrade to version 16.0.0 or later to mitigate this issue.

Affected Version(s)

js-libp2p < 16.0.0

References

https://github.com/libp2p/js-libp2p/security/advisories/G...
x_refsource_CONFIRM
https://github.com/libp2p/js-libp2p/pull/3520
x_refsource_MISC
https://github.com/libp2p/js-libp2p/commit/773dd80ded24db...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.