CVE-2026-115381: Allocation of Resources Without Limits or Throttling in bytecodealliance wasmtime
Description
CVE-2026-115381 is a medium severity vulnerability in bytecodealliance's wasmtime. It involves unbounded memory allocation in the wasmtime-wasi WASIp2 write-zeroes method of SinkOutputStream, which is the default stream when stdout/stderr are not configured. Malicious WebAssembly guests can exploit this to request large zero-filled writes, exhausting host memory and causing denial of service. The issue affects wasmtime versions before 36.0.17, versions from 37.0.0 up to but not including 48.0.4, and versions from 49.0.0 up to but not including 49.0.2.
CVSS v4.0
Score 5.9medium
Affected software
bytecodealliance
wasmtime
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in wasmtime arises from an unbounded memory allocation in the write-zeroes method of SinkOutputStream within the wasmtime-wasi WASIp2 implementation. SinkOutputStream is the default output stream used when stdout and stderr are not configured. A malicious WebAssembly guest can exploit this by requesting very large zero-filled writes, which leads to exhaustion of host memory resources and results in a denial of service condition. The affected versions are <36.0.17, >=37.0.0 <48.0.4, and >=49.0.0 <49.0.2.
Potential Impact
Successful exploitation allows a malicious WebAssembly guest to cause host memory exhaustion by requesting large zero-filled writes, leading to denial of service. There is no indication of code execution, data disclosure, or privilege escalation. The impact is limited to availability disruption.
Mitigation Recommendations
A fix is available in wasmtime versions 36.0.17, 48.0.4, and 49.0.2 and later. Users should upgrade to these or later versions to remediate the vulnerability. No other mitigation guidance is provided or required.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-10-22T11:25:27.610Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6ada64a34d27ba8daa756573
Added to database: 10/22/2026, 19:31:47 UTC
Last enriched: 10/22/2026, 20:31:25 UTC
Last updated: 10/22/2026, 20:31:25 UTC
Views: 2
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.