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

Why it is Yellow

• CVSS 5.9 medium
• On your watchlist: npm

Affected packages

References

• https://github.com/advisories/GHSA-3xpg-4rpp-hhhm
• https://github.com/nodejs/undici/security/advisories/GHSA-3xpg-4rpp-hhhm
• https://nvd.nist.gov/vuln/detail/CVE-2026-84890
• https://github.com/nodejs/undici/commit/2c7d7e1227043c644c4c32cfd1e276f4fd4fcb11
• https://github.com/nodejs/undici/commit/7aac7f12f757844763c8b8f1ab6e305e80d55838
• https://cna.openjsf.org/security-advisories.html
• https://github.com/nodejs/undici/releases/tag/v7.29.1
• https://github.com/nodejs/undici/releases/tag/v8.10.2
• https://github.com/advisories/GHSA-3xpg-4rpp-hhhm

Original description

### Impact The `interceptors.decompress()` interceptor decompresses HTTP response bodies according to the untrusted `Content-Encoding` header. The number of decompression layers is capped at 5, but the total decompressed output size is not bounded and there is no option to limit it. A malicious or faulty upstream can return a small compressed payload (a compression bomb) that expands to hundreds of megabytes or gigabytes in client memory, exhausting memory and causing the Node.js process to crash or become unresponsive. Any application using the decompress interceptor to read responses from untrusted or compromised upstreams is affected. ### Patches Upgrade to `7.29.1` or `8.10.2`. The interceptor now accepts a `maxSize` option (default 64 MiB) and rejects responses whose decompressed output exceeds it with a `ResponseExceededMaxSizeError`. ### Workarounds Once upgraded, set a conservative `maxSize` on the interceptor. Before upgrading, avoid using `interceptors.decompress()` with untrusted upstreams, or apply a custom interceptor that enforces a decompressed output size limit.