Nodejs Undici
CVE-2026-84933
undici's cache interceptor does not handle the Set-Cookie response header anywhere in its cache path, so it neither refuses to store nor strips that header. In shared cache mode, which is the default, an otherwise cacheable response that carries a Set-Cookie header, for example one marked with a public and max-age directive, is stored and then re-served to a later caller that matches the same cache key. As a result one caller's cookie is disclosed to a different caller, and an untrusted server can inject cookies into cached responses served to all subsequent callers. This violates the requirement that a shared cache must not store cookies. This affects undici versions from 7.0.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.
What this means for your business
- It affects Nodejs Undici. It matters if your company, or a supplier that handles your data, runs it.
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.2% chance of attack attempts being seen in the next 30 days, ranking above 16% of all known flaws.
What to do
- 1Check whether your company or your suppliers run Nodejs Undici, and which version. The affected versions are listed further down this page.
- 2If you do, apply the vendor's fix. A patch or vendor advisory has been published.
Fastnexa security experts
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Scoring
- CVSS
- 6.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N- Weakness
- CWE-200
- Assigned by
- ce714d77-add3-4f53-aff5-83d477b104bb
Dates
- Published
- 2026-09-04
- Last modified
- 2026-09-15
- Sources
- NVD
Affected products
- Nodejs Undici7.0.0 - 7.29.1, 8.0.0 - 8.10.2
As listed in the NVD configuration data. Not a statement about your estate.