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undici vulnerable to Denial of Service via orphaned RetryHandler response body

Moderate severity GitHub Reviewed Published Sep 4, 2026 in nodejs/undici • Updated Sep 29, 2026

Package

npm undici (npm)

Affected versions

>= 7.11.0, < 7.29.1
>= 8.0.0, < 8.10.2

Patched versions

7.29.1
8.10.2

Description

Impact

undici's RetryHandler can leave a response body pending indefinitely. When a retried request receives a non-retryable response after a truncated one, the original response.body held by the application is never settled, so reads such as response.body.text() hang and bodyTimeout does not fire. A malicious server can repeat this to accumulate pending promises and streams, leading to denial of service.

Patches

Patched in undici v7.29.1 and v8.10.2.

Workarounds

Impose an independent request deadline and destroy the response body when it expires. bodyTimeout alone does not prevent this.

References

@mcollina mcollina published to nodejs/undici Sep 4, 2026
Published by the National Vulnerability Database Sep 4, 2026
Published to the GitHub Advisory Database Sep 29, 2026
Reviewed Sep 29, 2026
Last updated Sep 29, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(28th percentile)

Weaknesses

Missing Release of Resource after Effective Lifetime

The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed. Learn more on MITRE.

CVE ID

CVE-2026-18149

GHSA ID

GHSA-pmjh-fq2x-6v4x

Source code

Credits

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