CVE-2026-86038

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: 0.2%, top 94% 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 weekElevated
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: Elevated riskExposed: 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. From 15.0.0 until 16.0.5, @libp2p/gossipsub uses the default StrictSign policy in packages/gossipsub/src/utils/buildRawMessage.ts, where validateToRawMessage verifies a signature with attacker-controlled msg.key but skips binding that key to msg.from when the claimed author is an RSA peer ID that does not inline a public key. An unauthenticated attacker can place a victim RSA peer ID in msg.from, sign the message with the attacker's private key, and supply the attacker's public key in msg.key, causing the message to be accepted and propagated as authored by the victim. Applications that trust message.from for validators, authorization, accounting, moderation, reputation, or audit logging can process attacker-controlled data under false origin attribution. The issue is fixed in version 16.0.5.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

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%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
0%
EPSS %ILE
6%
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

gossipsub: v16.0.5

Patch available: libp2p/js-libp2p gossipsub-v16.0.5

https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.5
github_commit Patch Available

commit cec2b1f349d1 (libp2p/js-libp2p)

Patch available: libp2p/js-libp2p transport-interop-libp2p-main-v1.0.39 (contains commit cec2b1f349d1)

https://github.com/libp2p/js-libp2p/commit/cec2b1f349d130065e561349a0336a239528267f
github_pr Patch Available

fix(gossipsub): validate the message key for all peer id types

Patch available: libp2p/js-libp2p transport-interop-libp2p-main-v1.0.39 (PR #3569 merged 2026-07-17)

https://github.com/libp2p/js-libp2p/pull/3569
github Patch Available🟡 PoC Available

Gossipsub StrictSign accepts attacker-signed messages as a victim RSA peer ID · Advisory · libp2p/js-libp2p · GitHub

https://github.com/libp2p/js-libp2p/security/advisories/GHSA-c3gv-825q-fvmp

Vendor Advisories for CVE-2026-86038(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 7× 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. 2026-09-19 21:27 UTCEG score recompute
  2. 2026-09-18 19:56 UTCEG score recompute
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-17 18:26 UTCEG score recompute
  5. 2026-09-17 17:57 UTCEG score recompute
  6. 2026-09-17 15:25 UTCEG score recompute
  7. 2026-09-17 15:24 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-86038?
CVE-2026-86038 is a high vulnerability published on September 17, 2026. libp2p is a JavaScript implementation of the libp2p networking stack. From 15.0.0 until 16.0.5, @libp2p/gossipsub uses the default StrictSign policy in packages/gossipsub/src/utils/buildRawMessage.ts, where validateToRawMessage verifies a signature with attacker-controlled msg.key but skips binding…
When was CVE-2026-86038 disclosed?
CVE-2026-86038 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-2026-86038 actively exploited?
CVE-2026-86038 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 94.1% of all scored CVEs.
What is the CVSS score of CVE-2026-86038?
CVE-2026-86038 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-86038?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-86038, 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.

Dependency Blast Radius

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