OpenJS Foundation undici up to 6.29.0/7.30.0/8.12.1 Established-Socket Error certificate validation

Summaryinfo

A vulnerability, which was classified as problematic, was found in OpenJS Foundation undici up to 6.29.0/7.30.0/8.12.1. The affected element is an unknown function of the component Established-Socket Error Handler. Such manipulation leads to certificate validation. This vulnerability is referenced as CVE-2026-87018. It is possible to launch the attack remotely. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in OpenJS Foundation undici up to 6.29.0/7.30.0/8.12.1 and classified as problematic. Affected by this issue is some unknown functionality of the component Established-Socket Error Handler. The manipulation with an unknown input leads to a certificate validation vulnerability. Using CWE to declare the problem leads to CWE-295. The product does not validate, or incorrectly validates, a certificate. Impacted is integrity. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-87018 since 09/08/2026. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1587.003.

Upgrading to version 6.29.1, 7.30.1 or 8.12.2 eliminates this vulnerability.

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Productinfo

Vendor

• OpenJS Foundation

Name

• undici

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21
• 6.22
• 6.23
• 6.24
• 6.25
• 6.26
• 6.27
• 6.28
• 6.29.0
• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21
• 7.22
• 7.23
• 7.24
• 7.25
• 7.26
• 7.27
• 7.28
• 7.29
• 7.30.0
• 8.12.0
• 8.12.1

CPE 2.3info

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CPE 2.2info

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