Is there a patch available for CVE-2026-54786?

Yes, a patch is available for CVE-2026-54786. Update the affected software to the latest version immediately.

Wasmtime CVE-2026-54786

Q: What is the CVSS score of CVE-2026-54786?

CVE-2026-54786 has a CVSS 4.0 base score of 2.3 (Low). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/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. EPSS exploitation probability: 0.2%.

EUVD-2026-41136 LOW

Missing Release of Resource after Effective Lifetime (CWE-772)

2026-07-01 GitHub_M

GHSA-3p27-qvp9-27qf

Information Disclosure Wasmtime Bytecodealliance

2.3

CVSS 4.0 · Vendor: GitHub_M

Severity by source

Vendor (GitHub_M) PRIMARY

2.3 LOW

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/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

vuln.today AI

4.3 MEDIUM

Guest requires low privileges and file-open permission; no confidentiality or integrity impact; availability impact is local to host file descriptor pool.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

4.0 AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Patch available

Jul 01, 2026 - 22:02 EUVD

Analysis Generated

Jul 01, 2026 - 20:52 vuln.today

DescriptionCVE.org

Wasmtime is a runtime for WebAssembly. All versions prior to 24.0.10; versions 25.0.0 through those before 36.0.11; versions 37.0.0 through those before 44.0.3; and versions 45.0.0 and 45.0.1 contain a native implementation of WASIp1 which suffers from a leak in the fd_renumber function where the file descriptor being renumbered to is not properly closed. Wasmtime's implementation erroneously only updated the table of descriptors for WASIp1 and didn't update the underlying table of descriptors used by the host. This behavior means that while fd_renumber works correctly from a guest's perspective it ends up leaking resources in the host that aren't cleaned up until the corresponding Store is destroyed. In a loop, guests can use fd_renumber to cause hosts to exhaust both resources and file descriptors. This bug only affects the native implementation of WASIp1, meaning that only runtimes which load core wasm modules and expose fd_renumber are affected. Runtimes are additionally only affected if they expose the ability to acquire a file descriptor, such as opening a file. For runtimes that deny access to files they are unaffected. This issue has been fixed in versions 24.0.10, 36.0.11, 44.0.3, and 45.0.2.

AnalysisAI

Resource exhaustion in Wasmtime's native WASIp1 implementation allows low-privileged WebAssembly guests to exhaust host-level file descriptors and OS resources by repeatedly invoking fd_renumber in a loop. The affected versions span four distinct release branches - all pre-24.0.10, 25.x-35.x, 37.x-44.x, and 45.0.0-45.0.1 - but only runtimes that both expose fd_renumber and grant guests the ability to open files are vulnerable. No public exploit code exists and the issue is not listed in CISA KEV; however, the attack is mechanically straightforward once the conditions are met, making patching the primary defense.

Technical ContextAI

Wasmtime (cpe:2.3:a:bytecodealliance:wasmtime) is Bytecode Alliance's production WebAssembly runtime, widely used in edge compute and server-side sandboxing. WASIp1 (WebAssembly System Interface preview 1) provides a POSIX-like syscall layer bridging wasm modules to host OS resources. The fd_renumber call is intended to atomically close the destination file descriptor and reassign the source FD to that slot - analogous to dup2(). Wasmtime's native WASIp1 implementation maintained two separate descriptor tables: a guest-visible one and an underlying host one. fd_renumber correctly updated the guest table but failed to close the corresponding host file descriptor entry (CWE-772: Missing Release of Resource after Effective Lifetime), meaning the host OS handle was never reclaimed. Resources accumulate until the associated Store object is destroyed, and in a tight loop a guest can rapidly exhaust the process's open file descriptor limit and OS resource quota.

RemediationAI

Upgrade to one of the vendor-released patched versions: 24.0.10, 36.0.11, 44.0.3, or 45.0.2, selecting the branch that matches your current deployment. Details are available at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-3p27-qvp9-27qf. If an immediate upgrade is not possible, the most effective compensating control is to configure the runtime to deny guest access to the host filesystem entirely - per the advisory, runtimes that do not expose file-open capability are unaffected, making this a clean mitigation with the trade-off of removing legitimate filesystem I/O for guests. Alternatively, rate-limiting or capping the number of fd_renumber calls a guest may make within a session can bound the leak rate, though this requires custom instrumentation and does not eliminate the underlying resource leak. No patch version should be inferred beyond those explicitly named above.