CVE-2026-87018undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation
Updated under an hour ago ()
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EPSS puts the chance of exploitation in the next 30 days at 0.18%, higher than 7% of scored CVEs.
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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.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-248, CWE-617
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.18% (percentile 7)
- Assigned by
- openjs
- NVD analysis
- Undergoing Analysis
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 15, 2026
Affected products
undici undici undici:undici (from the name) | from 4.2.1 before 6.29.1; 6.29.1 not affected; from 7.0.0 before 7.30.1; 7.30.1 not affected; from 8.0.0 before 8.12.2; 8.12.2 not affected | CNA record |
References
- https://github.com/nodejs/undici/security/advisories/GHSA-qrxm-fqhp-jwvm
- https://cna.openjsf.org/security-advisories.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.