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CVE-2026-54913

WebAssembly Micro Runtime: Missing `ref.null` heap-type validation in `load_init_expr` leaks host stack memory to the WebAssembly guest

Products / packages bytecodealliance wasm-micro-runtime

Published

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Severity and exploitation

Not in CISA KEV

KEV coverage does not rule out exploitation.

KEV checked 15/11/2026, 01:50:31 UTC
GitHub_M · CVSS:4.0 · 6.9
Assessment vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Severity

medium6.9

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Exploit reference published

Source-linked evidence; not proof of attacks in the wild or independent validation.

Remediation

Fix status not established

No structured fix or guidance is available here. Check the latest publisher advisory.

What this means

WebAssembly Micro Runtime versions prior to 2.4.5 have a missing validation in load_init_expr, potentially leaking host stack memory to the guest. A crafted module can cause uninitialized host-stack bytes to be copied into a readable value. The issue affects the classic and fast interpreters in the default no-GC configuration.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

bytecodealliance · GitHub_M

wasm-micro-runtime

1 range
GitHub_M version evidence

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affected

< 2.4.5

unaffected

unknown

Other versions: unknown

Automatic dependency matching is unavailable for this record. Use the product evidence and publisher’s instructions to check your installation.

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

No structured fix or remediation guidance is available here. Check the full source description and vendor’s latest advisory for a patch or workaround; do not assume another version is safe.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

The sources identify public exploit references. We have not independently tested them; their availability does not establish exploitation in the wild.

wasm-micro-runtime/wasm-micro-runtime · security/advisories/GHSA-frwm-5hpr-2hq2 ↗Attributed to CISA-ADP

Original source description

Read the full publisher description

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.

References

4 sources
wasm-micro-runtime/wasm-micro-runtime · security/advisories/GHSA-frwm-5hpr-2hq2
Public exploit referenceGitHub_M · CISA-ADP
wasm-micro-runtime/wasm-micro-runtime · commit c313279
PatchGitHub_M
wasm-micro-runtime/wasm-micro-runtime · commit e571797
PatchGitHub_M
wasm-micro-runtime/wasm-micro-runtime · releases/tag/WAMR-2.4.5
Release notesGitHub_M

Inside the record

Evidence available

Package identity · not supplied
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-54913

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-457 ↗

CWE-457: Use of Uninitialized Variable

GitHub_M

Related →
Contributing organizations · 2
GitHub_M

Assigning organization

2026-11-05
CISA-ADP

Additional data publisher

2026-11-09

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-54913

    Observed 2026-11-09T22:36:31.266Z · upstream updated 2026-11-09T22:27:04.987Z

    Prioritization updated

    before

    []

    after

    [
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-11-09T22:26:41.236903Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "poc"
      },
      {
        "name": "Automatable",
        "value": "no"
      },
      {
        "name": "Technical Impact",
        "value": "partial"
      }
    ]
  }
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.