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CVE-2026-115893VulnerabilityPublished

Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction

Affects wasmtimeSource GCVE Database

0
Authoritative record:CVE-2026-115893· Critical 9.9

Not known to be exploited · CVSS 9.9 Critical : upgrade to 36.0.19 as a priority.

Data as of 28 Oct 2026, 22:12 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, 48.0.7, 49.0.4
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

Upgrade wasmtime to 36.0.19; wasmtime to 48.0.7; wasmtime to 49.0.4.

Affected software

ProductAffectedFixed in
crates.iowasmtimeAffected
  • <36.0.19
Fixed in
  • 36.0.19
crates.iowasmtimeAffected
  • >=37.0.0 <48.0.7
Fixed in
  • 48.0.7
crates.iowasmtimeAffected
  • >=49.0.0 <49.0.4
Fixed in
  • 49.0.4

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

Description

## Summary When running with the Cranelift compiler backend on an aarch64 target, Wasmtime can compile a Wasm module with more than ~256k targets on one `br_table` instruction in a way that results in an incorrect conditional branch target. This conditional branch could then jump to arbitrary other code (at an user-controlled offset), leading to arbitrary sandbox escapes. ## Impact Any Wasmtime engine running on aarch64 with default settings can be forced to jump to arbitrary code by a user-controlled Wasm module. All versions of Wasmtime/Cranelift that support aarch64, since the initial release of that support in 2020 (before Wasmtime v1.0), are affected. ## Patches Wasmtime v36.0.19, v48.0.7, and v49.0.4 have been released which all fix this issue.

References

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