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CVE-2026-115386

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Memory Disclosure via fd_readdir

2.1 LowFix available

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
Passive

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

0.20%Unchanged since Oct 23, 2026
90%50%10%1%

What each source reports

CVE List Score used 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Memory Disclosure via fd_readdir

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
CVE-2026-115386
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
2.6 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
EUVDEUVD-2026-108314 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
EUVD-2026-108314
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-7vfm-vg2r-wpmh 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information...

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
GHSA-7vfm-vg2r-wpmh
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/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
2.6 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
NVD 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
CVE-2026-115386
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/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
2.6 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
Weakness
CWE-908
Updated
2026-11-02
OSV 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Memory Disclosure via fd_readdir

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
CVE-2026-115386
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-908
Updated
2026-11-02
OSVDEBIAN-CVE-2026-115386 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
DEBIAN-CVE-2026-115386
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/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-2026-0323 2.1

fd_readdir copies uninitialized struct padding into guest memory

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-96f6-r43r-8c24 For more information see the GitHub-hosted security advisory.

Record
RUSTSEC-2026-0323
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
OSVUBUNTU-CVE-2026-115386 2.1

Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 contains an information disclosure vulnerability in the WASIp1 fd_readdir implementation that copies uninitialized struct padding into guest memory. Guests with a preopened directory can list entries to receive three bytes of leftover host stack or heap memory per directory entry.

Record
UBUNTU-CVE-2026-115386
CVSS 4.0
2.1 LowCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
2.6 LowCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
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
Show 39 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-136.0.20+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-wasi
crates.io
0.0.0-0 up to 36.0.17, 37.0.0 up to 48.0.4, 49.0.0 up to 49.0.2
36.0.1748.0.449.0.2
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-2026-115386 is a low vulnerability (CVSS 2.1) in Bytecodealliance Wasmtime, published October 2, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.20%, the 9th percentile. Fixed in rust-wasmtime 36.0.20+dfsg-1.

References

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