Medium severity · published Oct 22, 2026
CVE-2026-115388
Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Memory Exhaustion DoS via wasmtime-wasi-http Outgoing Body Write
New
6.2
CVSS
0.1%
EPSS
No
On KEV
Description
wasmtime-wasi-http in Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not enforce the wasi:io/streams check-write allowance for WASIp2 outgoing HTTP bodies, so oversized writes succeed instead of trapping. A malicious guest can pass large buffers to write on outgoing-body resources, holding host allocations for the store's lifetime and exhausting host memory.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 1% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
WA
wasmtime · bytecodealliance
before 36.0.16; 37.0.0 before 48.0.3; 49.0.0 before 49.0.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-115388
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-115388
github.com
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-c9gc-w9vx-w86p
www.vulncheck.com
https://www.vulncheck.com/advisories/wasmtime-before-36.0.16-37.0.0-before-48.0.3-and-49.0.0-before-49.0.1-memory-exhaustion-dos-via-wasmtime-wasi-http-outgoing-body-write
More from wasmtime
10.0
CVE-2024-51745
Wasmtime is a fast and secure runtime for WebAssembly
9.9
CVE-2026-115893
Wasmtime: Cranelift backend on aarch64 can jump to incorrect target on large Wasm `br_table` instruction
9.9
CVE-2026-115889
Wasmtime: Bit-packing in Cranelift compiler causes silent overflow and miscompilation
9.9
CVE-2026-115384
Wasmtime 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 Stack Buffer Overflow
9.9
CVE-2026-34987
Wasmtime with Winch compiler backend on aarch64 may allow a sandbox-escaping memory access