Vulnerability · Published Oct 22, 2026 · Assigned by VulnCheck

CVE-2026-115386Wasmtime before 36.0.17, 37.0.0 before 48.0.4, and 49.0.0 before 49.0.2 Memory Disclosure via fd_readdir

Low 2.6

In plain English

A low-severity security flaw in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 10% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)2.6Low

Exploit odds (30 days)0.2%top 90.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Debian:13	rust-wasmtime	no fix listed	DEBIAN-CVE-2026-115386
Debian:14	rust-wasmtime	36.0.20+dfsg-1	DEBIAN-CVE-2026-115386
Ubuntu:24.04:LTS	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115386
Ubuntu:26.04:LTS	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115386
Ubuntu:26.10	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115386

Affected products (as reported)

Vendor	Product	Versions
bytecodealliance	wasmtime	0 – before 36.0.1737.0.0 – before 48.0.449.0.0 – before 49.0.2

Weakness: CWE-908 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N

References

GitHub Security Advisory (GHSA-96f6-r43r-8c24) vendor-advisory
VulnCheck Advisory: 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 third-party-advisory