Medium severity · published Oct 22, 2026
CVE-2026-115381
Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Unbounded Host Memory Allocation via SinkOutputStream write-zeroes
New
4.8
CVSS
0.2%
EPSS
No
On KEV
Description
Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an unbounded memory allocation in the wasmtime-wasi WASIp2 write-zeroes method of SinkOutputStream, the default stream used when stdout/stderr are not configured. A malicious WebAssembly guest can request huge zero-filled writes, exhausting host memory and causing denial of service.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
High
Privileges
Low
User interaction
Required
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 11% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WA
wasmtime · bytecodealliance
before 36.0.17; 37.0.0 before 48.0.4; 49.0.0 before 49.0.2 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115381
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115381
github.com
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-gqmc-89g8-p25r
www.vulncheck.com
https://www.vulncheck.com/advisories/wasmtime-before-36.0.17-37.0.0-before-48.0.4-and-49.0.0-before-49.0.2-unbounded-host-memory-allocation-via-sinkoutputstream-write-zeroes
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