Unbounded Memory Growth in Wasmtime by Bytecode Alliance
CVE-2026-119134

6.9MEDIUM

Key Information:

Vendor

Bytecodealliance

Status
Wasmtime
Vendor
CVE Published:
29 October 2026

What is CVE-2026-119134?

The vulnerability in Wasmtime affects versions prior to 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3, where the software limits component-model resource handle tables per instance only. Attackers can exploit this flaw by invoking resource.new and creating sub-components, which allows them to exceed the set limits, ultimately leading to unbounded host memory growth. This can have serious implications for system performance and stability, as it bypasses the intended resource allocation mechanisms.

Affected Version(s)

wasmtime 0 < 36.0.18

wasmtime 37.0.0 < 48.0.6

wasmtime 49.0.0 < 49.0.3

References

https://github.com/bytecodealliance/wasmtime/security/adv...
vendor-advisory
https://www.vulncheck.com/advisories/wasmtime-before-36.0...
third-party-advisory

CVSS V4

Score:
6.9
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

tschneidereit
fitzgen
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