undici vulnerable to downstream response desynchronization via retry interceptor
Summary
| CVE | CVE-2026-16728 |
|---|---|
| State | PUBLISHED |
| Assigner | openjs |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-29 21:17:46 UTC |
| Updated | 2026-08-04 14:06:21 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 6.5 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
EPSS: 0.001640000 probability, percentile 0.060290000 (date 2026-08-03)
Problem Types: CWE-444 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Primary | 6.5 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L |
| 3.1 | ce714d77-add3-4f53-aff5-83d477b104bb | Secondary | 4.8 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
| 3.1 | CNA | CVSS | 4.8 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
LowPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
LowAvailability
LowCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
NVD Known Affected Configurations (CPE 2.3)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Undici | Undici | affected 6.28.0 semver | Not specified |
| CNA | Undici | Undici | unaffected 6.28.0 semver | Not specified |
| CNA | Undici | Undici | affected 7.0.0 7.29.0 semver | Not specified |
| CNA | Undici | Undici | unaffected 7.29.0 semver | Not specified |
| CNA | Undici | Undici | affected 8.0.0 8.9.0 semver | Not specified |
| CNA | Undici | Undici | unaffected 8.9.0 semver | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| cna.openjsf.org/security-advisories.html | ce714d77-add3-4f53-aff5-83d477b104bb | cna.openjsf.org | Vendor Advisory |
| github.com/nodejs/undici/security/advisories/GHSA-8xcm-r25x-g524 | ce714d77-add3-4f53-aff5-83d477b104bb | github.com | Mitigation, Vendor Advisory |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: samuel871211 (en)
CNA: mcollina (en)
CNA: UlisesGascon (en)
There are currently no legacy QID mappings associated with this CVE.