Cross-user cookie disclosure via Set-Cookie caching
Published Sep 4, 2026 · Updated Sep 4, 2026
Information disclosure in Undici 7.0.0 through 7.29.0 and 8.0.0 through 8.10.1 allows remote attackers to expose cached cookies. The cache interceptor stores otherwise cacheable shared responses with Set-Cookie intact and re-serves that header to later callers matching the same cache key. Exploitation requires the shared cache interceptor and a cacheable response from an untrusted or multi-user upstream; private cache mode is unaffected.
Summary
What happened
Information disclosure in Undici 7.0.0 through 7.29.0 and 8.0.0 through 8.10.1 allows remote attackers to expose cached cookies. The cache interceptor stores otherwise cacheable shared responses with Set-Cookie intact and re-serves that header to later callers matching the same cache key. Exploitation requires the shared cache interceptor and a cacheable response from an untrusted or multi-user upstream; private cache mode is unaffected.
The record
- CVE
- CVE-2026-84933
- Published
- Sep 4, 2026
- Updated
- Sep 4, 2026
- Vendor
- Node.js
- Product
- Undici
- Classifications
- CWE-524, CWE-200
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 4, 2026CVE publishedPublication date reported by the CVE source.
- Sep 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=7.0.0 <7.29.1
- Affected versionversion=8.0.0 <8.10.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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