CVE-2026-86038
libp2p: Gossipsub StrictSign accepts attacker-signed messages as a victim RSA peer ID
Description
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.
INFO
Published Date :
Sept. 17, 2026, 4:18 p.m.
Last Modified :
Sept. 17, 2026, 6:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update @libp2p/gossipsub to version 16.0.5 or newer.
- Verify signature validation logic for RSA peer IDs.
- Ensure message origin is correctly authenticated.
- Review trust decisions based on message origin.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-86038.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-86038 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-86038
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-86038 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-86038 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 17, 2026
Action Type Old Value New Value Added Reference https://github.com/libp2p/js-libp2p/security/advisories/GHSA-c3gv-825q-fvmp Added SSVC {'id': 'CVE-2026-86038', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-17T17:24:10.344562Z'} -
New CVE Received by [email protected]
Sep. 17, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Added CWE CWE-345 Added CWE CWE-347 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/86xxx/CVE-2026-86038.json">CVE-2026-86038</a> Added Reference https://github.com/libp2p/js-libp2p/commit/cec2b1f349d130065e561349a0336a239528267f Added Reference https://github.com/libp2p/js-libp2p/pull/3569 Added Reference https://github.com/libp2p/js-libp2p/releases/tag/gossipsub-v16.0.5 Added Reference https://github.com/libp2p/js-libp2p/security/advisories/GHSA-c3gv-825q-fvmp