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VulnerabilityPublished Updated

CVE-2026-115892: bytecodealliance wasmtime · Type Confusion

Affects bytecodealliance wasmtimeSource CVE Database V5

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Not known to be exploited · CVSS 5.7 Medium : upgrade to 49.0.4 or 48.0.7 when convenient.

Data as of 29 Oct 2026, 19:15 UTC

CVSS 4.0 base score
5.7Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (GitHub_M)CVSS 4.05.7
EPSS
0.4% chance of exploitation in 30 days – higher than 37% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 49.0.4, 48.0.7
CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: 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 29 Oct 2026.

What to do

Upgrade wasmtime and bytecodealliance/wasmtime to 49.0.4 or 48.0.7.

Affected software

ProductAffectedFixed in
bytecodealliancewasmtimeAffected
  • >=49.0.0 <49.0.4
Fixed in
  • 49.0.4
bytecodealliancewasmtimeAffected
  • >=46.0.0 <48.0.7
Fixed in
  • 48.0.7
GitHubbytecodealliance/wasmtimepkg:github/bytecodealliance/wasmtimeOther threatsAffected
  • >=46.0.0 <48.0.7
  • >=49.0.0 <49.0.4
Fixed in
  • 48.0.7
  • 49.0.4

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

AI-suggested

This vulnerability is fixed in Wasmtime versions 48.0.7 and 49.0.4. Users should upgrade to at least these versions to remediate the issue. No additional mitigation steps are indicated by the vendor advisory.

Description

Wasmtime is a runtime for WebAssembly. From 46.0.0 until 48.0.7 and 49.0.4, lowering a host-created component-model stream or future into a guest can omit a required payload-type check after the value passes through guest code and returns through StreamAny, FutureAny, Val::Stream, Val::Future, or an equivalent typed reader. A malicious guest that controls exported function types or returned values can cause the host to pass the type-erased value to a guest expecting a different payload type, which panics the Wasmtime host. This issue is fixed in versions 48.0.7 and 49.0.4.

References

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