CVE-2022-39392
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Wasmtime vulnerable to out of bounds read/write with zero-memory-pages configuration
rank 23 = 0 + 19 + 0 + 4 + 0
rank@v1 · backlog
Someone is already using it
CISA KEV catalog · public proof-of-concept · FIRST EPSS
EPSS 0.00627 · without this subject the record ranks 23
What it costs you if it fires
NVD CVSS base score, then the CNA's own
CVSS 7.4, from NVD · without this subject the record ranks 4
It is getting worse, not staying still
FIRST EPSS series, rescorings and bad loads removed
no persisting rise in 365 days · without this subject the record ranks 23
How much of the world it touches
NVD CPE configurations
2 products in the CPE ranges · without this subject the record ranks 19
Someone else already set the date
CISA KEV remediation due date
no CISA due date · without this subject the record ranks 23
$27,600 = $4.99M incident cost x 0.8814887365328109 exposure x 0.00627 likelihood
udv@v1 · unaudited · wrong for you until you say what you run
$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.
Hindsight · the state
Foresight · where to check next
This record is one instance of CWE-119, improper restriction of operations within the bounds of a memory buffer. The index holds 14297 prior instances of this class, 57 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1
Sources disagree here.
Both shown, dated. We don't pick winners. disagreement-rules@v1
Running bytecodealliance wasmtime? Check your version
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Harm, if it fires from the vector and the weakness
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CISA KEV & Federal Remediation Deadline from the record and CISA
The fix, and how long it's been waiting.
Exploit Status & Known PoCs a ladder, not a score
Current rung: Nothing observed in held sources.
- RUNG 1Nothing observed in held sources
- RUNG 2Proof-of-concept published
- RUNG 3Exploited in the wild · CISA KEV listed
- RUNG 4Ransomware campaign use known
A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.
Attack path
What it is stated by the CNA
Wasmtime is a standalone runtime for WebAssembly. Prior to version 2.0.2, there is a bug in Wasmtime's implementation of its pooling instance allocator when the allocator is configured to give WebAssembly instances a maximum of zero pages of memory. In this configuration, the virtual memory mapping for WebAssembly memories did not meet the compiler-required configuration requirements for safely executing WebAssembly modules. receipt
Read the rest of the CNA's description
Wasmtime's default settings require virtual memory page faults to indicate that wasm reads/writes are out-of-bounds, but the pooling allocator's configuration would not create an appropriate virtual memory mapping for this meaning out of bounds reads/writes can successfully read/write memory unrelated to the wasm sandbox within range of the base address of the memory mapping created by the pooling allocator. This bug is not applicable with the default settings of the `wasmtime` crate. This bug can only be triggered by setting `InstanceLimits::memory_pages` to zero. This is expected to be a very rare configuration since this means that wasm modules cannot allocate any pages of linear memory. All wasm modules produced by all current toolchains are highly likely to use linear memory, so it's expected to be unlikely that this configuration is set to zero by any production embedding of Wasmtime. This bug has been patched and users should upgrade to Wasmtime 2.0.2. This bug can be worked around by increasing the `memory_pages` allotment when configuring the pooling allocator to a value greater than zero. If an embedding wishes to still prevent memory from actually being used then the `Store::limiter` method can be used to dynamically disallow growth of memory beyond 0 bytes large. Note that the default `memory_pages` value is greater than zero.
NVD's analysis a second authority
- severity
- 7.4 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- weakness
- CWE-119; CWE-125; CWE-787
- affected versions
- bytecodealliance wasmtime < 1.0.2; bytecodealliance wasmtime >= 2.0.0 < 2.0.2
- also scored by
- [email protected] 5.9 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:N
The CNA scored it 5.9 and NVD 7.4. Both are shown because both were published; we do not pick one.
check it yourself github.com github.com receipt
Movement the material steps
This score more than doubled inside 72 hours. Both observations are in the full history below.
Show all 32 observations
32 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt
The full biography
Exploit probability more than doubled between 2025-11-12 and 2025-11-14 (0.00107 → 0.00352) and the record had been public for 3 years, 10 months when this index was last written.
The pattern, elsewhere
This record is one instance of CWE-119, improper restriction of operations within the bounds of a memory buffer. The index holds 14297 prior instances of this class, 57 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]
"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1
14297 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.
No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.
Siblings and hubs
Records related to this one
No record cites this identifier and it carries no alias. Its defect family is below.
Its defect family
bytecodealliance wasmtime
Of the 2 records in this family, this is the only one whose title names vulnerable out bounds.
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Family membership: held values
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Browse the index from here
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What usually comes next
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