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CVE-2026-16729— undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields

Quick assessment

Affected
undici undici
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

undici undici是undici组织的一个HTTP客户端库。 undici 6.28.0之前版本、7.0.0版本至7.29.0之前版本和8.0.0版本至8.9.0之前版本存在输入验证错误漏洞，该漏洞源于setCookie函数未完全清理cookie属性，域值未检查分号且未解析数组条目未清理，攻击者可以注入额外cookie属性，可能导致绕过SameSite CSRF保护，或强制、剥离、覆盖Secure、HttpOnly和SameSite属性。

CVSS 4.8 · Medium EPSS 0.28% · P20

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici < 6.28.0 affected
6.28.0 unaffected
7.0.0< 7.29.0 affected
7.29.0 unaffected
8.0.0< 8.9.0 affected
8.9.0 unaffected
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I. Basic Information for CVE-2026-16729

Vulnerability Information
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Vulnerability Title
undici vulnerable to cookie attribute injection via unsanitized domain and unparsed setCookie fields
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输出中的特殊元素转义处理不恰当(注入)
Source: CVE Program / CVE List V5
Vulnerability Title
undici 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
undici undici是undici组织的一个HTTP客户端库。 undici 6.28.0之前版本、7.0.0版本至7.29.0之前版本和8.0.0版本至8.9.0之前版本存在输入验证错误漏洞，该漏洞源于setCookie函数未完全清理cookie属性，域值未检查分号且未解析数组条目未清理，攻击者可以注入额外cookie属性，可能导致绕过SameSite CSRF保护，或强制、剥离、覆盖Secure、HttpOnly和SameSite属性。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
undici undici 0 ~ 6.28.0 -

II. Public POCs for CVE-2026-16729

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III. Intelligence Information for CVE-2026-16729

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Vendor Advisories for CVE-2026-16729 (1)

Same Patch Batch · undici · 2026-07-29 · 5 CVEs total

CVE-2026-13697 7.4 HIGH undici vulnerable to cross-user information disclosure and parse-time crash via degenerate
CVE-2026-14643 5.9 MEDIUM undici vulnerable to cross-user information disclosure via whitespace around equals in Cac
CVE-2026-16728 4.8 MEDIUM undici vulnerable to downstream response desynchronization via retry interceptor
CVE-2026-15157 4.2 MEDIUM undici vulnerable to CRLF Injection via blob-like body 'type' property

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-74