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CVE-2026-115389

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API

1.0 LowFix available

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
High
Privileges needed
Low
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.15%Unchanged since Oct 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
CVE-2026-115389
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS 3.1
2.3 LowCVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-770
Updated
2026-11-02
EUVDEUVD-2026-108320 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
EUVD-2026-108320
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-3g9q-2gmg-4cvp 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately...

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
GHSA-3g9q-2gmg-4cvp
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
2.3 LowCVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-770
Updated
2026-11-02
NVD 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
CVE-2026-115389
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
2.3 LowCVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-770
Updated
2026-11-02
OSV 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 Denial of Service via Val API

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
CVE-2026-115389
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Weakness
CWE-770
Updated
2026-11-02
OSVDEBIAN-CVE-2026-115389 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
DEBIAN-CVE-2026-115389
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-03
OSVRUSTSEC-2026-0316 1.0

Dynamic record lifting can allocate beyond the hostcall fuel limit

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jqpg-j7w6-42pr For more information see the GitHub-hosted security advisory.

Record
RUSTSEC-2026-0316
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVUBUNTU-CVE-2026-115389 1.0

Wasmtime before 36.0.16, 37.0.0 before 48.0.3, and 49.0.0 before 49.0.1 does not adequately account for host allocations when lifting guest values through the dynamically-typed Val API, bypassing the hostcall fuel limit. A malicious WebAssembly guest can return crafted values that allocate at least ~100x more host memory than tracked, causing denial of service.

Record
UBUNTU-CVE-2026-115389
CVSS 4.0
1.0 LowCVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CVSS 3.1
2.3 LowCVSS:3.1/AV:A/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
rust-wasmtime
Debian:13
All versions, plus listed versions
26.0.1+dfsg-1026.0.1+dfsg-326.0.1+dfsg-426.0.1+dfsg-526.0.1+dfsg-6
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26.0.1+dfsg-726.0.1+dfsg-826.0.1+dfsg-927.0.0+dfsg-227.0.0+dfsg-327.0.0+dfsg-428.0.1+dfsg-128.0.1+dfsg-228.0.1+dfsg-329.0.1+dfsg-129.0.1+dfsg-229.0.1+dfsg-329.0.1+dfsg-429.0.1+dfsg-529.0.1+dfsg-629.0.1+dfsg-729.0.1+dfsg-836.0.11+dfsg-136.0.12+dfsg-136.0.12+dfsg-236.0.12+dfsg-336.0.13+dfsg-136.0.20+dfsg-136.0.5+dfsg-136.0.5+dfsg-236.0.5+dfsg-336.0.5+dfsg-436.0.5+dfsg-536.0.6+dfsg-136.0.6+dfsg-236.0.6+dfsg-336.0.6+dfsg-436.0.6+dfsg-536.0.6+dfsg-636.0.6+dfsg-736.0.7+dfsg-136.0.8+dfsg-136.0.9+dfsg-136.0.9+dfsg-2
None known
rust-wasmtime
Debian:14
before 36.0.20+dfsg-1, plus listed versions
26.0.1+dfsg-1026.0.1+dfsg-326.0.1+dfsg-426.0.1+dfsg-526.0.1+dfsg-6
Show 38 moreShow less
26.0.1+dfsg-726.0.1+dfsg-826.0.1+dfsg-927.0.0+dfsg-227.0.0+dfsg-327.0.0+dfsg-428.0.1+dfsg-128.0.1+dfsg-228.0.1+dfsg-329.0.1+dfsg-129.0.1+dfsg-229.0.1+dfsg-329.0.1+dfsg-429.0.1+dfsg-529.0.1+dfsg-629.0.1+dfsg-729.0.1+dfsg-836.0.11+dfsg-136.0.12+dfsg-136.0.12+dfsg-236.0.12+dfsg-336.0.13+dfsg-136.0.5+dfsg-136.0.5+dfsg-236.0.5+dfsg-336.0.5+dfsg-436.0.5+dfsg-536.0.6+dfsg-136.0.6+dfsg-236.0.6+dfsg-336.0.6+dfsg-436.0.6+dfsg-536.0.6+dfsg-636.0.6+dfsg-736.0.7+dfsg-136.0.8+dfsg-136.0.9+dfsg-136.0.9+dfsg-2
36.0.20+dfsg-1
wasmtime
crates.io
0.0.0-0 up to 36.0.16, 37.0.0 up to 48.0.3, 49.0.0 up to 49.0.1
36.0.1648.0.349.0.1
rust-wasmtime
Ubuntu:24.04:LTS
All versions, plus listed versions
10.0.1+dfsg-715.0.1+dfsg-416.0.0+dfsg-216.0.0+dfsg-3
None known
rust-wasmtime
Ubuntu:26.10
All versions, plus listed versions
36.0.5+dfsg-136.0.13+dfsg-1
None known
rust-wasmtime
Ubuntu:26.04:LTS
All versions, plus listed versions
26.0.1+dfsg-326.0.1+dfsg-428.0.1+dfsg-329.0.1+dfsg-536.0.5+dfsg-1
None known

History

History
RecordedChangedSources
affectedOSV
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-115389 is a low vulnerability (CVSS 1.0) in Bytecodealliance Wasmtime, published September 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.15%, the 4th percentile. Fixed in rust-wasmtime 36.0.20+dfsg-1.

References

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