CVE-2026-16728
undici vulnerable to downstream response desynchronization via retry interceptor
Description
undici's retry interceptor can deliver a response whose body length does not match the Content-Length header exposed to the application after a retry or resume of a partial response. 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 malicious or faulty upstream can return a partial response with a mismatched framing header, close the socket early, and have the retry interceptor assemble a body of a different length while the original Content-Length stays attached. Applications that use the retry interceptor and forward upstream headers and bodies downstream, such as proxies or gateways, may then emit an invalid HTTP response with a stale Content-Length, leading to downstream response desynchronization, connection hangs, or response corruption. Exploitation requires the retry interceptor enabled, an upstream returning a mismatched partial response, and a downstream forwarder that does not remove or recalculate Content-Length. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.
INFO
Published Date :
July 29, 2026, 9:17 p.m.
Last Modified :
Aug. 4, 2026, 2:06 p.m.
Remotely Exploit :
Yes !
Source :
ce714d77-add3-4f53-aff5-83d477b104bb
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | ce714d77-add3-4f53-aff5-83d477b104bb | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update undici to version 6.28.0 or later.
- Update undici to version 7.29.0 or later.
- Update undici to version 8.9.0 or later.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-16728.
| URL | Resource |
|---|---|
| https://cna.openjsf.org/security-advisories.html | Vendor Advisory |
| https://github.com/nodejs/undici/security/advisories/GHSA-8xcm-r25x-g524 | Mitigation Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-16728 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-16728
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-16728 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-16728 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Aug. 04, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L Added CPE Configuration OR *cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:* versions from (including) 7.0.0 up to (excluding) 7.29.0 *cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:* versions from (including) 8.0.0 up to (excluding) 8.9.0 *cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:* versions up to (excluding) 6.28.0 Added Reference Type openjs: https://cna.openjsf.org/security-advisories.html Types: Vendor Advisory Added Reference Type openjs: https://github.com/nodejs/undici/security/advisories/GHSA-8xcm-r25x-g524 Types: Mitigation, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 30, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-16728', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-30T14:20:06.238159Z'} -
New CVE Received by ce714d77-add3-4f53-aff5-83d477b104bb
Jul. 29, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'undici', 'product': 'undici', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '6.28.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.28.0', 'versionType': 'semver'}, {'status': 'affected', 'version': '7.0.0', 'lessThan': '7.29.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.29.0', 'versionType': 'semver'}, {'status': 'affected', 'version': '8.0.0', 'lessThan': '8.9.0', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '8.9.0', 'versionType': 'semver'}], 'packageURL': 'pkg:npm/undici', 'defaultStatus': 'unaffected'}] Added Description undici's retry interceptor can deliver a response whose body length does not match the Content-Length header exposed to the application after a retry or resume of a partial response. 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 malicious or faulty upstream can return a partial response with a mismatched framing header, close the socket early, and have the retry interceptor assemble a body of a different length while the original Content-Length stays attached. Applications that use the retry interceptor and forward upstream headers and bodies downstream, such as proxies or gateways, may then emit an invalid HTTP response with a stale Content-Length, leading to downstream response desynchronization, connection hangs, or response corruption. Exploitation requires the retry interceptor enabled, an upstream returning a mismatched partial response, and a downstream forwarder that does not remove or recalculate Content-Length. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0. Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Added CWE CWE-444 Added Reference https://cna.openjsf.org/security-advisories.html Added Reference https://github.com/nodejs/undici/security/advisories/GHSA-8xcm-r25x-g524