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CVE-2026-84933

8.2, high

undici Exposure of Sensitive Information Vulnerability

NVD (opens in a new tab) CVE.org (opens in a new tab)
CVSS
8.2, high high CVSS v3.1
EPSS, next 30 days
0.3% higher than 21.5% of scored CVEs
Exploitation
No public evidence
Published
4 Sept 2026a month ago

Description

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.

Details

Vendor
Undici
Product
undici
Weakness
CWE-200 (opens in a new tab)
Status
Analyzed
Updated
15 Sept 2026
Assigner
ce714d77-add3-4f53-aff5-83d477b104bb

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

References 2

Advisories 2

The kind is read from NVD's tags where present and from the shape of the URL otherwise, so treat it as a hint.

Other Undici CVEs

Every Undici CVE we hold

Same vendor in what we hold, not a known link between the flaws.

  • CVE-2026-84961 undici's BalancedPool constructor passes its entire options object through an internal deep-clone that serializes and reparses the value… EPSS 0.1% 9.1, critical
  • CVE-2026-85014 undici's experimental WebSocketStream client crashes the whole Node.js process when a remote peer closes the TCP connection without a… EPSS 0.4% 7.5, high

Beyond this page

Is CVE-2026-84933 in your network?

This page tells you how dangerous CVE-2026-84933 is out there. Whether it sits on one of your devices, only a scan of your own network can tell. That is what our systems do, every day, for the companies we protect.

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    Find it before attackers do

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  • EXYS7950 KONDRA

    Detect it if it's exploited

    Until the patch is applied, Kondra monitors your network, events and endpoints in real time. It keeps an inventory of the software installed on every endpoint, and its anomaly detection rules flag what an attacker does once inside.

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Check your exposure

Assembled from the NVD 2.0 API, the CISA Known Exploited Vulnerabilities Catalog and FIRST EPSS. Scores are as of our last collection on 17 Oct 2026, not the live upstream state.