What is CVE-2020-18378?

CVE-2020-18378 is a medium-severity vulnerability in Webassembly Binaryen, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2023-08-22.

How severe is CVE-2020-18378?

Medium severity. CVSS v3 base score is 6.5 out of 10.

NULL pointer dereference in Webassembly Binaryen

CVE-2020-18378

A NULL pointer dereference was discovered in SExpressionWasmBuilder::makeBlock in wasm/wasm-s-parser.c in Binaryen 1.38.26. A crafted wasm input can cause a segmentation fault, leading to denial-of-service, as demonstrated by wasm-as.

Published 2023-08-22 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (47.1th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 47th percentile — 47.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Webassembly Binaryen — versions 1.38.26

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

github.com/WebAssembly/binaryen/issues/1900 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2020-18378?: CVE-2020-18378 is a medium-severity vulnerability in Webassembly Binaryen, classified under NULL Pointer Dereference. CVSS score: 6.5/10. Published 2023-08-22.
How severe is CVE-2020-18378?: Medium severity. CVSS v3 base score is 6.5 out of 10.