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TI-2026-85542 Aliases CVE-2026-54913

WAMR leaks uninitialized host stack memory via unvalidated ref.null heap type

Priority LOW 30CWE-457Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
Information disclosure
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-457 and the CVSS impact.

Summary

WebAssembly Micro Runtime (WAMR) before 2.4.5 does not validate the heap-type byte of a ref.null instruction in load_init_expr when WASM_ENABLE_GC=0, so the classic and fast interpreters accept a non-reference heap type. A crafted module can declare an i64, f64, or v128 global initialized this way, which copies uninitialized host stack bytes into a value readable by the guest, CWE-457. An unauthenticated remote attacker can read this host memory by supplying a crafted WebAssembly module, and the disclosure is four bytes for i64 or f64 globals and up to twelve bytes for each v128 global.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Description from the CNA

WebAssembly Micro Runtime (WAMR) is a lightweight standalone WebAssembly (Wasm) runtime. Prior to 2.4.5, load_init_expr in core/iwasm/interpreter/wasm_loader.c accepts a non-reference heap-type byte for ref.null when WASM_ENABLE_GC=0, while the local WASMValue cur_value union is not zero-initialized and setting ref_index writes only part of it. A crafted module can declare an i64, f64, or v128 global initialized through the invalid ref.null form, causing push_const_expr_stack and the later global initialization path to copy uninitialized host-stack bytes into a value readable by the guest. The classic and fast interpreters are affected in the default no-GC configuration; the GC-enabled path validates heap types. The disclosure is four bytes for i64 or f64 globals and up to twelve bytes for each v128 global. This issue is fixed in version 2.4.5.

Why it matters now

EPSS 0.00301 23rd percentileScored 2026-11-07
Fix Fixed wasm-micro-runtime (bytecodealliance): 2.4.5

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
bytecodealliancewasm-micro-runtimebefore 2.4.52.4.5Patch availableCNA
  • wasm-micro-runtime Vendorbytecodealliance Affected before 2.4.5 Fixed in 2.4.5 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:webassembly_micro_runtime:*:*:*:*:*:*:*:*——bytecodealliance
  • cpe:2.3:a:bytecodealliance:webassembly_micro_runtime:*:*:*:*:*:*:*:* Versions — — ·bytecodealliance

Remediation

Update bytecodealliance wasm-micro-runtime to version 2.4.5, which fixes the issue. The sources list no fixed version for other releases.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

  • Fix · CNA wasm-micro-runtime (bytecodealliance) Fixed in 2.4.5

Timeline

  1. 2026-11-05 Threatist record created from CVE-2026-54913
  2. 2026-11-07 Priority changed: MEDIUM → LOW

References

Other 4

  • 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