CVE-2026-16729Network attack vector

Cookie attribute injection via unsanitized setCookie fields

Published Jul 29, 2026 · Updated Jul 29, 2026

Cookie attribute injection in Node.js undici before 6.28.0, 7.0.0 through 7.28.0, and 8.0.0 through 8.8.0 allows remote attackers to alter cookies. The setCookie serializer accepts semicolons in domain and emits unsanitized unparsed entries, allowing appended attributes to reach Set-Cookie output. Exploitation requires an application to pass attacker-controlled values into those fields and permits CSRF-protection bypass or forced, stripped, or overridden cookie attributes.

CVSS severity4.8
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cookie attribute injection in Node.js undici before 6.28.0, 7.0.0 through 7.28.0, and 8.0.0 through 8.8.0 allows remote attackers to alter cookies. The setCookie serializer accepts semicolons in domain and emits unsanitized unparsed entries, allowing appended attributes to reach Set-Cookie output. Exploitation requires an application to pass attacker-controlled values into those fields and permits CSRF-protection bypass or forced, stripped, or overridden cookie attributes.

The record

CVE
CVE-2026-16729
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
Node.js
Product
Undici
Classifications
CWE-74, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 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.

  1. Affected versionversion=0 <6.28.0
  2. Affected versionversion=7.0.0 <7.29.0
  3. Affected versionversion=8.0.0 <8.9.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Node.js · Undiciversion=0 <6.28.0; version=7.0.0 <7.29.0; version=8.0.0 <8.9.0

Published CVSS scores

4.8OpenJSCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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