CVE-2026-86040

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 69% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

libp2p is a JavaScript implementation of the libp2p networking stack. Prior to 11.0.26, @libp2p/floodsub accepts unauthenticated RPC frames on /floodsub/1.0.0 through PeerStreams.attachInboundStream in packages/floodsub/src/peer-streams.ts without protobuf element limits, then processRpc and processRpcSubOpt in packages/floodsub/src/floodsub.ts synchronously process the subscriptions array without a per-frame cap. A single bounded-size frame can decode into millions of empty subscription entries that block the event loop, while hundreds of thousands of unique-topic SUBSCRIBE entries allocate PeerSet objects in this.topics that are not removed after peer removal or stop. Empty entries cause CPU exhaustion but do not grow this.topics; persistent memory growth requires unique topics. The subscription path bypasses message signature validation and the message-only processing queue, allowing a remote peer to cause sustained CPU denial of service, memory exhaustion, out-of-memory termination, and node unavailability. The issue is fixed in version 11.0.26.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
31%
KEV
Not listed

Published

September 17, 2026

Last Modified

September 17, 2026

Advisory Details (4)

Auto-updated Sep 17, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

floodsub: v11.0.26

Patch available: libp2p/js-libp2p floodsub-v11.0.26

https://github.com/libp2p/js-libp2p/releases/tag/floodsub-v11.0.26
github_commit Patch Available

commit fb9e8a76e9ac (libp2p/js-libp2p)

Patch available: libp2p/js-libp2p transport-interop-libp2p-main-v1.0.39 (contains commit fb9e8a76e9ac)

https://github.com/libp2p/js-libp2p/commit/fb9e8a76e9ac75924928fae4ce11d00f68320a83
github_pr Patch Available

fix(floodsub): apply decode limits and clean up the topic map

Patch available: libp2p/js-libp2p transport-interop-libp2p-main-v1.0.39 (PR #3568 merged 2026-07-16)

https://github.com/libp2p/js-libp2p/pull/3568
github Patch Available🟡 PoC Available

Unbounded RPC decode + synchronous subscription processing in @libp2p/floodsub allows unauthenticated DoS · Advisory · libp2p/js-libp2p · GitHub

https://github.com/libp2p/js-libp2p/security/advisories/GHSA-cvfg-hcf3-ggwv

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 8× in last 7d / 8× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-20 00:51 UTCEG score recompute
  2. 2026-09-18 22:39 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 20:27 UTCEG score recompute
  5. 2026-09-17 19:30 UTCEG score recompute
  6. 2026-09-17 17:57 UTCEG score recompute
  7. 2026-09-17 15:25 UTCEG score recompute
  8. 2026-09-17 15:24 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-86040?
CVE-2026-86040 is a high vulnerability published on September 17, 2026. libp2p is a JavaScript implementation of the libp2p networking stack. Prior to 11.0.26, @libp2p/floodsub accepts unauthenticated RPC frames on /floodsub/1.0.0 through PeerStreams.attachInboundStream in packages/floodsub/src/peer-streams.ts without protobuf element limits, then processRpc and…
When was CVE-2026-86040 disclosed?
CVE-2026-86040 was first published in the National Vulnerability Database on September 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-86040 actively exploited?
CVE-2026-86040 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 68.8% of all scored CVEs.
What is the CVSS score of CVE-2026-86040?
CVE-2026-86040 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-86040?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-86040, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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