Vulnerability · Published Mar 12, 2026 · Assigned by openjs
CVE-2026-1527undici is vulnerable to CRLF Injection via upgrade option
Medium 4.6
In plain English
A medium-severity security flaw in undici from undici. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
ImpactWhen an application passes user-controlled input to the upgrade option of client.request(), an attacker can inject CRLF sequences (\r\n) to: * Inject arbitrary HTTP headers * Terminate the HTTP request prematurely and smuggle raw data to non-HTTP services (Redis, Memcached, Elasticsearch) The vulnerability exists because undici writes the upgrade value directly to the socket without validating for invalid header characters: // lib/dispatcher/client-h1.js:1121 if (upgrade) { header += `connection: upgrade\r\nupgrade: ${upgrade}\r\n` }
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | nodejs | 1:24.14.1-2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs | 1:24.14.1-2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-devel | 1:24.14.1-2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-devel | 1:24.14.1-2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-docs | 1:24.14.1-2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-docs | 1:24.14.1-2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-full-i18n | 1:24.14.1-2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-full-i18n | 1:24.14.1-2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-libs | 1:24.14.1-2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-libs | 1:24.14.1-2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-nodemon | 3.0.3-1.module_el8.10.0+4061+f8ceeab9 | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-nodemon | 3.0.3-3.module_el9.7.0+209+ecf6523e | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-packaging | 2021.06-6.module_el8.10.0+4086+70facd4a | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-packaging | 2021.06-6.module_el9.7.0+209+ecf6523e | ALSA-2026:7350 |
| AlmaLinux:8 | nodejs-packaging-bundler | 2021.06-6.module_el8.10.0+4086+70facd4a | ALSA-2026:7670 |
| AlmaLinux:9 | nodejs-packaging-bundler | 2021.06-6.module_el9.7.0+198+8bf605ba | ALSA-2026:7350 |
| AlmaLinux:10 | nodejs24-docs | 1:24.14.1-2.el10_1 | ALSA-2026:7675 |
| AlmaLinux:10 | nodejs24-npm | 1:11.11.0-1.24.14.1.2.el10_1 | ALSA-2026:7675 |
| AlmaLinux:8 | npm | 1:11.11.0-1.24.14.1.2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | npm | 1:11.11.0-1.24.14.1.2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| AlmaLinux:8 | v8-13.6-devel | 3:13.6.233.17-1.24.14.1.2.module_el8.10.0+4160+4819ac42 | ALSA-2026:7670 |
| AlmaLinux:9 | v8-13.6-devel | 3:13.6.233.17-1.24.14.1.2.module_el9.7.0+222+ef1c61e1 | ALSA-2026:7350 |
| Debian:13 | node-undici | no fix listed | DEBIAN-CVE-2026-1527 |
| Debian:14 | node-undici | 7.24.5+dfsg+~cs3.2.0-1 | DEBIAN-CVE-2026-1527 |
| Rocky Linux:8 | nodejs-nodemon | 0:3.0.3-1.module+el8.10.0+2084+ab509703 | RLSA-2026:7670 |
| Rocky Linux:9 | nodejs-nodemon | 0:3.0.3-3.module+el9.7.0+40025+0e0cf6b2 | RLSA-2026:7350 |
| Rocky Linux:8 | nodejs-packaging | 0:2021.06-6.module+el8.10.0+40048+6d99f608 | RLSA-2026:7670 |
| Rocky Linux:9 | nodejs-packaging | 0:2021.06-6.module+el9.7.0+40052+e32ea525 | RLSA-2026:7350 |
| Rocky Linux:10 | nodejs24 | 1:24.14.1-2.el10_1 | RLSA-2026:7675 |
| Ubuntu:24.04:LTS | node-undici | no fix listed | UBUNTU-CVE-2026-1527 |
| Ubuntu:25.10 | node-undici | no fix listed | UBUNTU-CVE-2026-1527 |
| Ubuntu:26.04:LTS | node-undici | no fix listed | UBUNTU-CVE-2026-1527 |
| Ubuntu:26.10 | node-undici | no fix listed | UBUNTU-CVE-2026-1527 |
| npm | undici | 7.24.0 | GHSA-4992-7rv2-5pvq |
| npm | undici | 6.24.0 | GHSA-4992-7rv2-5pvq |
Affected products (as reported)
Weakness: CWE-93 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N