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VulnerabilityPublished Updated

CVE-2026-115889: Rust wasmtime · Wasmtime is a runtime for WebAssembly

Affects rust-wasmtimeSource GCVE Database

0
Authoritative record:CVE-2026-115889· Critical 9.9

Not known to be exploited · CVSS 9.9 Critical · fixed in 36.0.19 : patch rust-wasmtime as a priority.

Data as of 28 Oct 2026, 22:43 UTC

CVSS 3.1 base score
9.9Critical
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 36.0.19
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10rust-wasmtimepkg:deb/ubuntu/rust-wasmtime?arch=source&distro=stonkingOther threatsAffected
  • =36.0.5+dfsg-1
  • =36.0.13+dfsg-1
Fixed in–
Ubuntu 26.04 LTSrust-wasmtimepkg:deb/ubuntu/rust-wasmtime?arch=source&distro=resoluteOther threatsAffected
  • 26.0.1+dfsg-3 – 36.0.5+dfsg-1
5 affected builds
Fixed in–
Ubuntu 24.04 LTSrust-wasmtimepkg:deb/ubuntu/rust-wasmtime?arch=source&distro=nobleOther threatsAffected
  • 10.0.1+dfsg-7 – 16.0.0+dfsg-3
4 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Wasmtime to version 36.0.19 or later, or 43.0.0 or later, where the vulnerability is fixed. No other mitigation is indicated or required according to the provided data.

Description

CVE-2026-115889 affects the Wasmtime runtime for WebAssembly, specifically its Cranelift compiler backend. Versions prior to 36.0.19 and 43.0.0 have a vulnerability where SSA value indices are bit-packed in a way that can overflow silently in release builds when compiling large or specially crafted Wasm functions. This overflow can cause incorrect intermediate representation references, leading to arbitrary miscompilation, type confusion, and potentially allowing attacker-controlled effects to escape the Wasm sandbox. The issue is fixed in versions 36.0.19 and 43.0.0.

References

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