# CVE-2026-87018: node-undici: undici is an HTTP client library for Node.js CVE-2026-87018 is fixed in 21 products on 1 platform, first by DEBIAN-CVE-2026-87018, released November 1, 2026. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2026-87018 - Priority: High - CVSS: 7.5 (high) - EPSS: 0.0019 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Oct 15, 2026 ## Description 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | node-undici Debian 14 | 8.12.2+dfsg+~cs3.2.3-1 | [DEBIAN-CVE-2026-87018](https://patchblox.com/security/data/fix/linux/debian-cve-2026-87018.md) | Nov 1, 2026 | | Linux | nodejs22 amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-debuginfo amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-debugsource amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-devel amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-docs amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-full-i18n amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-libs amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-libs-debuginfo amzn 2023 | 1:22.23.4-1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs22-npm amzn 2023 | 1:10.9.9-1.22.23.4.1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | nodejs24 amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-debuginfo amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-debugsource amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-devel amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-docs amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-full-i18n amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-libs amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-libs-debuginfo amzn 2023 | 1:24.22.1-1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | nodejs24-npm amzn 2023 | 1:11.19.1-1.24.22.1.1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | | Linux | v8-12.4-devel amzn 2023 | 3:12.4.254.21-1.22.23.4.1.amzn2023.0.1 | [ALAS2023-2026-3328](https://patchblox.com/security/data/fix/linux/alas2023-2026-3328.md) | Nov 7, 2026 | | Linux | v8-13.6-devel amzn 2023 | 3:13.6.233.17-1.24.22.1.1.amzn2023.0.1 | [ALAS2023-2026-3330](https://patchblox.com/security/data/fix/linux/alas2023-2026-3330.md) | Nov 7, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. 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