Security readout for executives and security teams
Plain-English summary
Binaryen 1.38.26 can crash when processing a maliciously crafted WebAssembly input. The documented impact is denial of service, not data theft or code execution. Business urgency depends on whether Binaryen tools process untrusted files in CI, developer tooling, SaaS upload paths, or analysis services.
Executive priority
Prioritize this as a moderate availability risk. It is most important for services that automatically process untrusted WebAssembly. If Binaryen is only used locally by trusted developers, urgency is lower, but version inventory and vendor guidance checks are still warranted.
Technical view
CVE-2020-18378 is a CWE-476 NULL pointer dereference in SExpressionWasmBuilder::makeBlock in wasm/wasm-s-parser.c. The source description says crafted wasm input can trigger a segmentation fault, demonstrated through wasm-as. CVSS 3.1 is 6.5 with high availability impact and no confidentiality or integrity impact.
Likely exposure
Exposure is most likely where Binaryen 1.38.26, especially wasm-as, processes WebAssembly inputs supplied by users, customers, repositories, or automated build jobs. The CVE affected metadata is incomplete, so teams should verify actual Binaryen use rather than assume broad product exposure.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation. Public technical discussion exists through the referenced Binaryen GitHub issue. Practical abuse would be availability-focused: causing a process that parses a crafted wasm input to crash.
Researcher notes
The key uncertainty is incomplete affected-product metadata: the CVE record lists n/a fields while the description names Binaryen 1.38.26. Do not expand scope beyond Binaryen evidence. Validate exposure through dependency and toolchain inventory, then focus on untrusted input processing boundaries.
Mitigation direction
- Inventory Binaryen and wasm-as usage in build, upload, and analysis workflows.
- Avoid processing untrusted wasm inputs with Binaryen 1.38.26 on shared systems.
- Check Binaryen and CVE guidance for official fixed versions or mitigations.
- Run wasm parsing jobs in isolated, restartable workers with resource limits.
- Treat crashes from wasm inputs as security-relevant denial-of-service events.
Validation and detection
- Confirm whether Binaryen 1.38.26 is installed or bundled anywhere.
- Identify workflows that pass external wasm inputs to wasm-as.
- Review public upload or repository ingestion paths for wasm processing.
- Check logs for segmentation faults during Binaryen wasm parsing.
- Track the referenced GitHub issue and CVE record for vendor guidance.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-476: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-18378 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/WebAssembly/binaryen/issues/1900CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
NULL Pointer Dereference
NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.