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Fencer Vulns
medium 5.0

CVE-2026-54786 json

Wasmtime: Leak in WASIp1 `fd_renumber` implementation

published 2026-06-15 4 mo ago modified 2026-10-25 15 d ago also EUVD-2026-41136 , GHSA-3p27-qvp9-27qf , JLSEC-2026-1367 , RUSTSEC-2026-0182

cvss
5.0
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 30%
public exploits
0
none known

Summary

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.

Patch / fix

  • crates.io wasmtime-wasi 24.0.10, 36.0.11, 44.0.3, 45.0.2
  • julia Wasmtime_jll 46.0.1+0
  • bytecodealliance wasmtime 24.0.10, 36.0.11, 44.0.3, 45.0.2
  • rust-wasmtime Debian 14 36.0.11+dfsg-1

debian advisories DEBIAN-CVE-2026-54786

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-54786 updated

Wasmtime: Wasmtime: Leak in WASIp1 `fd_renumber` implementation

  • Red Hat Connectivity Link 1 rhcl-1/wasm-shim-rhel9 Red Hat Enterprise Linux 10 virt-firmware-rs 26.4-1.el10
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images rust 1.96.0-4.hum1
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 30% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 2.3 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
GitHub 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
CNA 4.0 2.3 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
NVD 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L
OSV 3.1 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
crates.io wasmtime-wasi
<24.0.10
>=45.0.0, <45.0.2
>=25.0.0, <36.0.11
>=37.0.0, <44.0.3
>=0.0.0-0, <24.0.10
24.0.10
45.0.2
36.0.11
44.0.3
julia Wasmtime_jll
<46.0.1+0
46.0.1+0

Affected products

  • bytecodealliance wasmtime

Classification

Weakness
  • CWE-772 Missing Release of Resource after Effective Lifetime
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.