7.5

CVE-2026-34946: bytecodealliance wasmtime

CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-34946DEBIAN-CVE-2026-34946CGA-39hg-mrv8-qjxp
Published 09-04-2026Last modified 09-04-2026
Open JSON

Vulnerability summary

CVE-2026-34946 is a high (CVSS 7.5) vulnerability in bytecodealliance wasmtime. EPSS estimates a 0.42% chance of exploitation in the next 30 days, higher than 35.3% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.42%
0%100%
Low · +0.07 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-GQQ8-QCR7-4HJJ

Timeline

  1. 09-04-2026
    PublishedVulnerability first disclosed.
  2. 09-04-2026
    Last modifiedVulnerability information updated.

Description

Wasmtime is a runtime for WebAssembly. From 25.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's Winch compiler contains a vulnerability where the compilation of the table.fill instruction can result in a host panic. This means that a valid guest can be compiled with Winch, on any architecture, and cause the host to panic. This represents a denial-of-service vulnerability in Wasmtime due to guests being able to trigger a panic. The specific issue is that a historical refactoring changed how compiled code referenced tables within the table.* instructions. This refactoring forgot to update the Winch code paths associated as well, meaning that Winch was using the wrong indexing scheme. Due to the feature support of Winch the only problem that can result is tables being mixed up or nonexistent tables being used, meaning that the guest is limited to panicking the host (using a nonexistent table), or executing spec-incorrect behavior and modifying the wrong table. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.

CVSS metrics

9 scores · 7 sources · 2 versions

EPSS trend

Probability

0.42%

Chance of exploitation in the next 30 days

Percentile

35%

Versus all other CVEs

30-day change

+0.07 pp

From 0.36% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.42%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard5 products
  • washAll versions (No fix recorded)
  • wasmcloud< 2.0.4-r0
  • wizer< 11.0.3-r10
  • yara-x< 1.15.0-r2
  • zed< 0.228.0-r3
Wolfi5 products
  • washAll versions (No fix recorded)
  • wasmcloud< 2.0.4-r0
  • wizer< 11.0.3-r10
  • yara-x< 1.15.0-r2
  • zed< 0.228.0-r3
Bytecodealliance1 product
  • wasmtime≥ 43.0.0, < 44.0.1 | ≥ 25.0.0, < 36.0.7 | ≥ 37.0.0, < 42.0.2 | ≥ 43.0.0, < 43.0.1
Crates.Io1 product
  • wasmtime≥ 25.0.0, < 36.0.7 | ≥ 37.0.0, < 42.0.2 | ≥ 43.0.0, < 43.0.1
Debian1 product
  • rust-wasmtimeAll versions (No fix recorded) | < 36.0.7+dfsg-1
Ubuntu1 product
  • rust-wasmtimeAll versions (No fix recorded)

6 vendors · 14 products

References

10 links