7.5

CVE-2026-49866: libp2p js-libp2p

CVSS: 7.5v3.1HighDeferred
AliasesGHSA-cwc9-cp4j-mcvv
Published 08-07-2026Last modified 09-07-2026
Open JSON

Vulnerability summary

CVE-2026-49866 is a high (CVSS 7.5) vulnerability in libp2p js-libp2p. EPSS estimates a 0.63% chance of exploitation in the next 30 days, higher than 49.2% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.63%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 08-07-2026
    PublishedVulnerability first disclosed.
  2. 09-07-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.63%

Chance of exploitation in the next 30 days

Percentile

49%

Versus all other CVEs

30-day change

0.00 pp

From 0.63% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.63%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

@libp2p1 product
  • gossipsub< 16.0.0
Libp2p1 product

2 vendors · 2 products

References

6 links