CVE-2026-11525Network attack vector

Cookie-policy downgrade via permissive SameSite substring matching

Published Jun 17, 2026 · Updated Jun 17, 2026

Cookie parsing in Node.js Undici before 6.27.0, 7.0.0 through 7.27.0, and 8.0.0 through 8.4.0 allows remote attackers to weaken SameSite policy. The Set-Cookie parser searches untrusted SameSite values for Strict, Lax, or None substrings and normalizes malformed matches to those tokens. Exposure requires an application to consume a malicious server response and then forward or trust the parsed sameSite attribute, degrading cookie policy integrity.

CVSS severity3.7
Low
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cookie parsing in Node.js Undici before 6.27.0, 7.0.0 through 7.27.0, and 8.0.0 through 8.4.0 allows remote attackers to weaken SameSite policy. The Set-Cookie parser searches untrusted SameSite values for Strict, Lax, or None substrings and normalizes malformed matches to those tokens. Exposure requires an application to consume a malicious server response and then forward or trust the parsed sameSite attribute, degrading cookie policy integrity.

The record

CVE
CVE-2026-11525
Published
Jun 17, 2026
Updated
Jun 17, 2026
Vendor
Node.js
Product
Undici
Classifications
CWE-183, CAPEC-71, CAPEC-3, CAPEC-120, CAPEC-43
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <6.26.0
  2. Affected versionversion=7.0.0 <7.28.0
  3. Affected versionversion=8.0.0 <8.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Node.js · Undiciversion=0 <6.26.0; version=7.0.0 <7.28.0; version=8.0.0 <8.5.0

Published CVSS scores

3.7OpenJS FoundationCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-183Permissive List of Allowed Inputs
CAPEC-71Using Unicode Encoding to Bypass Validation Logic
CAPEC-3Using Leading 'Ghost' Character Sequences to Bypass Input Filters
CAPEC-120Double Encoding
CAPEC-43Exploiting Multiple Input Interpretation Layers

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo