Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-11525— undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching

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.

Node.js undici是Node.js基金会开源的一个HTTP/1.1客户端。 Node.js undici 6.26.0之前版本、7.28.0之前版本和8.5.0之前版本存在输入验证错误漏洞，该漏洞源于解析Set-Cookie标头时，将包含Strict、Lax或None子字符串的SameSite属性值接受为标准值，而非严格执行RFC 6265的精确匹配，可能导致恶意服务器将cookie的SameSite策略弱化为更宽松的设置。

CVSS 3.7 · Low EPSS 0.24% · P14

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 6

VendorProduct Version RangeStatus
undici undici < 6.26.0 affected
6.26.0 unaffected
7.0.0< 7.28.0 affected
7.28.0 unaffected
8.0.0< 8.5.0 affected
8.5.0 unaffected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-11525

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
undici vulnerable to Set-Cookie SameSite attribute downgrade via permissive substring matching
Source: CVE Program / CVE List V5
Vulnerability Description
Impact: When undici parses a Set-Cookie header, it accepts any SameSite attribute value that contains Strict, Lax, or None as a substring, rather than the case-insensitive exact match specified by RFC 6265. Non-spec values are silently mapped to one of the three standard tokens. For example, SameSite=NoneOfYourBusiness is parsed as None (the most permissive setting), and SameSite=StrictLax is parsed as Lax (a downgrade from Strict). Affected applications are those that consume Set-Cookie headers from server responses (for example via undici's fetch or proxy code paths) and then forward or rely on the parsed sameSite attribute. A malicious or non-compliant server can coerce the consumer's view of a cookie's SameSite policy to a weaker value, silently degrading the SameSite enforcement the cookie is supposed to provide. This was introduced in undici 5.15.0 when the cookies feature was added. Patches: Upgrade to undici v6.26.0, v7.28.0 or v8.5.0. Workarounds: After parsing a Set-Cookie header, validate that the resulting sameSite attribute is one of 'Strict', 'Lax', or 'None' (exact, case-insensitive) before forwarding or relying on it.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
宽松定义的白名单
Source: CVE Program / CVE List V5
Vulnerability Title
Node.js undici 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Node.js undici是Node.js基金会开源的一个HTTP/1.1客户端。 Node.js undici 6.26.0之前版本、7.28.0之前版本和8.5.0之前版本存在输入验证错误漏洞，该漏洞源于解析Set-Cookie标头时，将包含Strict、Lax或None子字符串的SameSite属性值接受为标准值，而非严格执行RFC 6265的精确匹配，可能导致恶意服务器将cookie的SameSite策略弱化为更宽松的设置。
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 ~ 6.26.0 -

II. Public POCs for CVE-2026-11525

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-11525

请登录查看更多情报信息。

Vendor Advisories for CVE-2026-11525 (1)

Same Patch Batch · undici · 2026-06-17 · 8 CVEs total

CVE-2026-9675 7.5 HIGH undici WebSocket client vulnerable to denial of service via cumulative fragment bypass
CVE-2026-12151 7.5 HIGH undici WebSocket client vulnerable to denial of service via fragment count bypass
CVE-2026-6734 7.5 HIGH undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse
CVE-2026-9697 7.4 HIGH undici vulnerable to TLS certificate validation bypass via dropped requestTls in SOCKS5 Pr
CVE-2026-9679 5.9 MEDIUM undici vulnerable to HTTP header injection via Set-Cookie percent-decoding
CVE-2026-9678 5.9 MEDIUM undici vulnerable to cross-user information disclosure via shared cache whitespace bypass
CVE-2026-6733 3.7 LOW undici vulnerable to HTTP response queue poisoning via keep-alive socket reuse

IV. Related Vulnerabilities

Same product: undici
Same vendor: undici
Same weakness: CWE-183

V. Comments for CVE-2026-11525

No comments yet

Leave a comment