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Advisory record · GHSA-9prg-84vf-g5fc

`wasi-http` p3: Guests can set incorrect content-length for spliced response bodies

CVSS 6.9 MediumEPSS 0.0019 · 9th percentile

Published by the GitHub Advisory Database at 19 Oct 2026, 12:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
wasmtime-wasi-httpcrates.io>=46.0.0, <48.0.7 || >=49.0.0, <49.0.448.0.7, 49.0.4
Identifiers
GHSA-9prg-84vf-g5fc · CVE-2026-121439 · RUSTSEC-2026-0375
Weakness (CWE)
CWE-444
Tags
Published
19 Oct 2026
Updated
4 Nov 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The wasmtime-wasi-http crate is vulnerable in versions 46.0.0 up to 48.0.7 and 49.0.0 up to 49.0.4. A guest component can set an incorrect content-length on spliced response bodies, which is a MEDIUM severity issue (CVSS 5.3). The source gives few details beyond this, and no attack requirements or impacts are described. Upgrade to version 48.0.7 or 49.0.4.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
6.9 Medium 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N CNA (VulnCheck)
  • CISA KEV Not listed.
  • EPSS 0.0019, the 9th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:24 UTC First seen by agentprime
  2. 31 Oct 2026, 14:24 UTC Confirmed by OSV
  3. 3 Nov 2026, 14:38 UTC Confirmed by the CVE List
  4. 3 Nov 2026, 15:25 UTC Confirmed by NVD

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.