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Vulnerabilities

Vulnerability · CVE-2026-58494

Wasmtime: WASI hard links bypass wasmtime-wasi's FilePerms for destination

Published Oct 16, 2026 · catalog updated Oct 16, 2026 · Wasmtime: WASI hard links

Check if you run it

No confirmed exploitation is on record for CVE-2026-58494. EPSS is 0.17%. Act only if a listed version of Wasmtime: WASI hard links is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Wasmtime: WASI hard links).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.17%
Remediation
Version ranges on file
Affected products
cargo wasmtime-wasi · crates.io wasmtime-wasi · rust wasmtime-wasi

## Summary Wasmtime's WASI filesystem implementation lets a guest with a read-only source file capability overwrite that file by hard-linking it into another preopen that allows file writes. An attacker who can run a WASI guest can bypass per-preopen and modify host files that were exposed as . This attack is possible through the wasip1, wasip2, and wasip3 interfaces to the WASI filesystem. This attack is also possible through an indirection of renaming a hardlink into another preopen. ### Details documents as the maximum permissions usable for files in that preopen. However, hard-link creation and renaming only checked directory mutation for permission, and not whether the file permissions matched. This makes an attack possible where: * a read-only file exists in a preopen with only FilePerms::READ * a hardlink named , with destination to the , is created in a preopen with FilePerms::READ | FilePerms::WRITE * the attacker opens the file for writing, in which they can overwrite The same attack is possible by way of renaming: * a read-only file exists in a preopen with only FilePerms::READ * a hardlink named , with destination to the , is created in that same preopen * the file is renamed into a preopen with FilePerms::READ | FilePerms::WRITE * the attacker opens the file for writing, in which they can overwrite Symbolic links are not a vector for this attack because the wasi-filesystem interfaces already enforces that the destination for a symlink is under the same preopen. We do not believe there are any other vectors to this attack because there are no other wasi filesystem interfaces that take multiple borrows of a descriptor resource for e.g. the source and destination in different descriptors. ### Remediation The definition of and in wasmtime-wasi's now have an additional permissions check that ensures the source and destination values for the directory permissions and the file permissions are identical. ### Impact Only wasmtime-wasi embeddings that use a combi

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cargo wasmtime-wasiversion unspecified
  • crates.io wasmtime-wasi0 → 24.0.11
  • crates.io wasmtime-wasi25.0.0 → 36.0.12
  • crates.io wasmtime-wasi37.0.0 → 45.0.3
  • crates.io wasmtime-wasi46.0.0 → 46.0.1
  • rust wasmtime-wasi< 24.0.11
  • rust wasmtime-wasi>= 25.0.0, < 36.0.12
  • rust wasmtime-wasi>= 37.0.0, < 45.0.3
  • rust wasmtime-wasi>= 46.0.0, < 46.0.1

How to fix CVE-2026-58494

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-58494. EPSS is 0.17%. Act only if a listed version of Wasmtime: WASI hard links is installed.

Which versions are affected?

Compare what you have installed with 0 → 24.0.11, 25.0.0 → 36.0.12, 37.0.0 → 45.0.3, 46.0.0 → 46.0.1, < 24.0.11, >= 25.0.0, < 36.0.12. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-281; CWE-863: Incorrect Authorization. EPSS 0.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 16, 2026 · GitHub Advisory Database

    Detected

    ## Summary Wasmtime's WASI filesystem implementation lets a guest with a read-only source file capability overwrite that file by hard-linking it into another preopen that allows file writes. An attacker who can run a WASI guest can bypass per-preopen and modify host files that were exposed as . This attack is possible through the wasip1, wasip2, and wasip3 interfaces to the WASI filesystem. This a

  2. Oct 16, 2026 · GitHub Advisory Database

    Fix available

    wasmtime-wasi fixed in 24.0.11; wasmtime-wasi fixed in 36.0.12; wasmtime-wasi fixed in 45.0.3; wasmtime-wasi fixed in 46.0.1

  3. Oct 16, 2026 · GitHub Advisory Database

    Fix available

    wasmtime-wasi fixed in 24.0.11

  4. Oct 16, 2026 · GitHub Advisory Database

    Fix available

    wasmtime-wasi fixed in 36.0.12

  5. Oct 16, 2026 · GitHub Advisory Database

    Fix available

    wasmtime-wasi fixed in 45.0.3

  6. Oct 16, 2026 · GitHub Advisory Database

    Fix available

    wasmtime-wasi fixed in 46.0.1

  7. Oct 16, 2026 · GitHub Advisory Database

    Updated

    ## Summary Wasmtime's WASI filesystem implementation lets a guest with a read-only source file capability overwrite that file by hard-linking it into another preopen that allows file writes. An attacker who can run a WASI guest can bypass per-preopen and modify host files that were exposed as . This attack is possible through the wasip1, wasip2, and wasip3 interfaces to the WASI filesystem. This a

Sources

  • CVE.orgVulnerability recordCVE-2026-58494

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-58494

    30-day exploitation probability 0.2%

    first.org
  • GitHub Advisory DatabasePackage advisoryGHSA-4ch3-9j33-3pmj

    GitHub Advisory Database record mirrored by OSV.

    github.com
  • GitLab Advisory DatabasePackage advisoryCVE-2026-58494

    Wasmtime's WASI filesystem implementation lets a guest with a read-only source file capability overwrite that file by hard-linking it into another preopen that allows file writes. An attacker who can run a WASI guest can bypass WasiCtxBuilder per-preopen FilePerms and modify host files that were exposed as FilePerms::READ. This attack is possible through the wasip1, wasip2, and wasip3 interfaces t

    advisories.gitlab.com
  • OpenSSF OSV / OSV ScannerPackage advisoryGHSA-4ch3-9j33-3pmj

    Wasmtime: WASI hard links bypass wasmtime-wasi's FilePerms for destination

    osv.dev

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.