CVE-2020-18378Network attack vector

Denial of service via parser null dereference

Published Aug 22, 2023 · Updated Oct 3, 2024

NULL pointer dereference in Binaryen 1.38.26 allows attackers to crash wasm-as with a crafted WebAssembly text input. SExpressionWasmBuilder::makeBlock in wasm/wasm-s-parser.cpp dereferences a null pointer while converting attacker-controlled block syntax into an internal block expression. Exploitation requires the crafted file to be processed by wasm-as, after which the affected process terminates with a segmentation fault without reported data disclosure or modification.

CVSS severity6.5
Medium
EPSS probability0.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Binaryen 1.38.26 allows attackers to crash wasm-as with a crafted WebAssembly text input. SExpressionWasmBuilder::makeBlock in wasm/wasm-s-parser.cpp dereferences a null pointer while converting attacker-controlled block syntax into an internal block expression. Exploitation requires the crafted file to be processed by wasm-as, after which the affected process terminates with a segmentation fault without reported data disclosure or modification.

The record

CVE
CVE-2020-18378
Published
Aug 22, 2023
Updated
Oct 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-476, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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