undici's setCookie function does not fully sanitize cookie attributes. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a domain value is not checked for semicolons and entries in the unparsed array are not sanitized, so attacker-influenced input can inject additional cookie attributes. For example, a domain value containing a semicolon can append attributes such as SameSite, and an unparsed entry can inject attributes such as HttpOnly, without the caller setting them. Applications that pass user-controlled input to these fields, such as multi-tenant or reverse-proxy servers that scope session cookies to a tenant-supplied domain, can have SameSite CSRF protections bypassed, or the Secure, HttpOnly, and SameSite attributes forced, stripped, or overridden. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.
Advisories
Source ID Title
Github GHSA Github GHSA GHSA-v3r7-h72x-cjcm undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 06 Aug 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-140
References
Metrics threat_severity

None

threat_severity

Moderate


Wed, 29 Jul 2026 18:45:00 +0000

Type Values Removed Values Added
First Time appeared Undici
Undici undici
Vendors & Products Undici
Undici undici

Wed, 29 Jul 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 29 Jul 2026 17:15:00 +0000

Type Values Removed Values Added
Description undici's setCookie function does not fully sanitize cookie attributes. In undici before 6.28.0, from 7.0.0 up to before 7.29.0, and from 8.0.0 up to before 8.9.0, a domain value is not checked for semicolons and entries in the unparsed array are not sanitized, so attacker-influenced input can inject additional cookie attributes. For example, a domain value containing a semicolon can append attributes such as SameSite, and an unparsed entry can inject attributes such as HttpOnly, without the caller setting them. Applications that pass user-controlled input to these fields, such as multi-tenant or reverse-proxy servers that scope session cookies to a tenant-supplied domain, can have SameSite CSRF protections bypassed, or the Secure, HttpOnly, and SameSite attributes forced, stripped, or overridden. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.
Title undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields
Weaknesses CWE-74
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: openjs

Published:

Updated: 2026-07-29T18:08:16.149Z

Reserved: 2026-07-23T05:44:24.720Z

Link: CVE-2026-16729

cve-icon Vulnrichment

Updated: 2026-07-29T18:08:11.679Z

cve-icon NVD

Status : Analyzed

Published: 2026-07-29T17:16:51.123

Modified: 2026-08-05T15:18:55.053

Link: CVE-2026-16729

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-07-29T16:45:57Z

Links: CVE-2026-16729 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-06T01:30:05Z

Weaknesses