Answer in brief
CVE-2026-84890 records a Medium severity (CVSS 5.9) 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), undici (npm), undici (npm), undici (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.9. 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.
The current feed maps undici/undici (generic), undici (npm), undici (npm), undici (npm) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:* | Not reported | Not reported |
| 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 |
| undicinpm | >=7.15.0,<7.29.1 | 7.29.1 |
| undicinpm | >=8.0.0,<8.10.2 | 8.10.2 |
| undicinpm | >=7.15.0 <7.29.1 | 7.29.1 |
| undicinpm | >=8.0.0 <8.10.2 | 8.10.2 |
Published upstream
Sep 4, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 29, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 4, 2026
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.