CVE-2026-87018

undici is an HTTP client library for Node.js. In versions 4.2.1 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, the client process crashes when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with a certificate-altname error, but undici's established-socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught assertion that terminates the Node.js process, affecting both the HTTP/1.1 and HTTP/2 paths. A malicious or compromised HTTPS endpoint reached through undici or the global fetch() can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process, and exploitation needs no CA compromise because the attacker controls the endpoint and can present two ordinary valid certificates. Only TLS 1.2 is affected, since TLS 1.3 does not support renegotiation. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. As a workaround, restrict outbound connections to TLS 1.3 so renegotiation cannot occur, when the target endpoints support it.
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

History

19 Oct 2026, 20:41

Type Values Removed Values Added
First Time Nodejs
Nodejs undici
CPE cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*
References () https://cna.openjsf.org/security-advisories.html - () https://cna.openjsf.org/security-advisories.html - Vendor Advisory
References () https://github.com/nodejs/undici/security/advisories/GHSA-qrxm-fqhp-jwvm - () https://github.com/nodejs/undici/security/advisories/GHSA-qrxm-fqhp-jwvm - Vendor Advisory

15 Oct 2026, 19:17

Type Values Removed Values Added
New CVE

Information

Published : 2026-10-15 19:17

Updated : 2026-10-19 20:41


NVD link : CVE-2026-87018

Mitre link : CVE-2026-87018

CVE.ORG link : CVE-2026-87018


JSON object : View

Products Affected

nodejs

  • undici
CWE
CWE-248

Uncaught Exception

CWE-617

Reachable Assertion