CVE-2026-16728Network attack vector

Response desynchronization via stale retry framing

Published Jul 29, 2026 · Updated Jul 29, 2026

HTTP response desynchronization in Undici before 6.28.0 allows remote attackers to corrupt forwarded responses through partial replies. The interceptors.retry() path preserves the first response Content-Length while assembling a shorter body after a resumed range request and early socket close. Affected 7.x releases are before 7.29.0, and affected 8.x releases are before 8.9.0; exploitation also requires a downstream forwarder that retains the stale header, resulting in response corruption, connection hangs, or desynchronization.

CVSS severity4.8
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP response desynchronization in Undici before 6.28.0 allows remote attackers to corrupt forwarded responses through partial replies. The interceptors.retry() path preserves the first response Content-Length while assembling a shorter body after a resumed range request and early socket close. Affected 7.x releases are before 7.29.0, and affected 8.x releases are before 8.9.0; exploitation also requires a downstream forwarder that retains the stale header, resulting in response corruption, connection hangs, or desynchronization.

The record

CVE
CVE-2026-16728
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
Node.js
Product
Undici
Classifications
CWE-444, T1499.004
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

4.8OpenJS Foundation CNACVSS: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:N/I:L/A:L

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-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1499.004Application or System Exploitation

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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