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TI-2026-79471 Aliases CVE-2026-115386GHSA-7vfm-vg2r-wpmh

Wasmtime fd_readdir discloses uninitialized host memory to guests

Priority LOW 11CWE-908Published · Updated

Key facts

Attack vector
Network
Privileges required
Low
User interaction
Passive
Attack complexity
Low
Attack requirements
Present
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Partial Red Hat: 2 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-908 and the CVSS impact.

Summary

Wasmtime before 36.0.17, from 37.0.0 before 48.0.4, and from 49.0.0 before 49.0.2 contains an information disclosure flaw in the WASIp1 fd_readdir implementation. It copies uninitialized struct padding into guest memory (CWE-908). A guest with a preopened directory can list its entries and receive three bytes of leftover host stack or heap memory per entry.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00197 9th percentileScored 2026-11-07
Fix Partial wasmtime (bytecodealliance): 36.0.17, 48.0.4, 49.0.2Red Hat: 2 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
bytecodealliancewasmtimebefore 36.0.17; 37.0.0 to before 48.0.4; 49.0.0 to before 49.0.236.0.17, 48.0.4, 49.0.2Patch availableCNA
  • wasmtime Vendorbytecodealliance Affected before 36.0.17; 37.0.0 to before 48.0.4; 49.0.0 to before 49.0.2 Fixed in 36.0.17, 48.0.4, 49.0.2 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:*:*:*——bytecodealliance
  • cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:*:*:* Versions — — ·bytecodealliance

Remediation

Upgrade Wasmtime to 36.0.17, 48.0.4, or 49.0.2 for the matching release line. Red Hat gives no fix plan for Red Hat Connectivity Link 1 and Red Hat Enterprise Linux 10.

Written with Claude Haiku 5.5 from the sources below · 2026-10-28

  • Fix · CNA wasmtime (bytecodealliance) Fixed in 36.0.17, 48.0.4, 49.0.2

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    bytecodealliance wasmtime 36.0.17, 48.0.4, 49.0.2

    3 records Highest priority Priority LOW 3 LOW

    Other records, highest priority first

    • TI-2026-79466 Unbounded memory allocation in Wasmtime SinkOutputStream write-zeroesPriority LOW 26
    • TI-2026-79465 Resource exhaustion in Wasmtime WASI poll_oneoff ignores fuel limitsPriority LOW 22
    Show all 3 records →

Vendor assessments

Red Hat

Red Hat rating: Low. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Connectivity Link 1AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-22 Threatist record created from CVE-2026-115386
  2. 2026-10-22 Alias added: GHSA-7vfm-vg2r-wpmh
  3. 2026-10-23 Affected versions changed · Red Hat
  4. 2026-10-23 CVSS score added · Red Hat
  5. 2026-10-23 CISA SSVC decision points changed

References

Advisory 1

  • TI-2026-85541 WAMR fast interpreter loader heap overflow via constant deduplication mismatch CVSS 4.0HIGH 8.8
  • TI-2024-16741 An issue in bytecodealliance wasm-micro-runtime before v.b3f728c and fixed in commit… CVSS 3.1HIGH 8.8
  • TI-2024-22658 An out-of-bound memory read vulnerability was discovered in Bytecode Alliance… CVSS 3.1HIGH 7.5
  • TI-2024-18300 wasm-micro-runtime (aka WebAssembly Micro Runtime or WAMR) 06df58f is vulnerable to NULL… CVSS 3.1HIGH 7.5
  • TI-2023-26034 An heap overflow vulnerability was discovered in Bytecode alliance wasm-micro-runtime… CVSS 3.1HIGH 7.5
  • TI-2025-33969 WebAssembly Micro Runtime's `--addr-pool` option allows all IPv4 addresses when subnet mask is not specified CVSS 4.0MEDIUM 6.9
See all 97 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences