undici vulnerable to Denial of Service via unbounded decompression of compressed responses (CVE-2026-84890) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-84890

undici vulnerable to Denial of Service via unbounded decompression of compressed responses

Answer in brief

CVE-2026-84890 records a Unknown severity vulnerability in undici vulnerable to Denial of Service via unbounded decompression of compressed responses. The current sources do not mark it as known exploited. The current feed maps undici/undici (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 4, 2026Updated Sep 4, 2026Source checked Sep 4, 2026First seen by HOL Sep 4, 2026Material review Sep 4, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps undici/undici (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
undici/undicigeneric	>=7.15.0 <7.29.1 \|\| >=8.0.0 <8.10.2	7.29.1, 8.10.2

Recommended response

Check inventory. Check lockfiles and deployed manifests for undici/undici.
Review the reported fix. Update undici/undici to 7.29.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 4, 2026

Sources and claim methodology

Upstream source description

undici's decompress interceptor decompresses response bodies according to the untrusted Content-Encoding header. While the number of content-encoding layers is capped, the total decompressed output size is unbounded and there is no configuration option to limit it. A malicious or faulty upstream can therefore return a small compressed payload, a compression bomb, that expands to hundreds of megabytes or more in client memory, an asymmetric resource consumption that can exhaust memory and crash the process. This affects undici versions from 7.15.0 up to 7.29.1 and from 8.0.0 up to 8.10.2. Users should upgrade to undici 7.29.1 or 8.10.2.

Quoted source text, attributed separately from HOL analysis.