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Unbounded memory growth in Wasmtime via resource handles

Priority LOW 29CWE-770Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
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-770.

Summary

Wasmtime before 36.0.18, from 37.0.0 before 48.0.6, and from 49.0.0 before 49.0.3 caps component-model resource handle tables only per component instance. Handle allocations are not charged to any ResourceLimiter or StoreLimits, so a malicious guest can repeatedly call resource.new and instantiate sub-components to exceed the cap many times over (CWE-770). This causes unbounded host memory growth.

Written with Claude Haiku 5.5 from the sources below · 2026-10-30

Description from the CNA

Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 caps component-model resource handle tables only per component instance and does not charge handle allocations to any ResourceLimiter or StoreLimits. A malicious guest can repeatedly call resource.new and instantiate sub-components to exceed the per-instance cap many times over, causing unbounded host memory growth.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00153 4th percentileScored 2026-11-07
Fix Partial wasmtime (bytecodealliance): 36.0.18, 48.0.6, 49.0.3Red 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 36.0.18; 37.0.0 to before 48.0.6; 49.0.0 to before 49.0.336.0.18, 48.0.6, 49.0.3Patch availableCNA
  • wasmtime Vendorbytecodealliance Affected before 36.0.18; 37.0.0 to before 48.0.6; 49.0.0 to before 49.0.3 Fixed in 36.0.18, 48.0.6, 49.0.3 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

Fixed versions are Wasmtime 36.0.18, 48.0.6 and 49.0.3. The sources list no fixed version for Red Hat Connectivity Link 1 and Red Hat Enterprise Linux 10.

Written with Claude Haiku 5.5 from the sources below · 2026-10-30

  • Fix · CNA wasmtime (bytecodealliance) Fixed in 36.0.18, 48.0.6, 49.0.3

Fixed in the same release

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

  • Release ·

    bytecodealliance wasmtime 36.0.18, 48.0.6, 49.0.3

    2 records Highest priority Priority LOW 2 LOW

    Other records, highest priority first

    • TI-2026-82648 Wasmtime HTTP target smuggling lets guests reach disallowed hostsPriority LOW 11

Vendor assessments

Red Hat

Red Hat rating: Moderate. 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. 2026-10-29 Threatist record created from CVE-2026-119134
  2. 2026-10-29 Alias added: GHSA-59gg-q3p6-vwvr
  3. 2026-10-29 CISA SSVC decision points changed
  4. 2026-10-29 Priority changed: MEDIUM → LOW
  5. 2026-10-30 Affected versions changed · Red Hat
  6. 2026-10-30 CVSS score added · Red Hat

References

  • 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