What is CVE-2026-33131?

CVE-2026-33131 is a high-severity vulnerability in H3js H3, classified under Authentication Bypass by Spoofing. CVSS score: 7.4/10. Published 2026-03-20.

How severe is CVE-2026-33131?

High severity. CVSS v3 base score is 7.4 out of 10.

Vulnerability in H3js H3

CVE-2026-33131

H3 is a minimal H(TTP) framework. Versions 2.0.0-0 through 2.0.1-rc.14 contain a Host header spoofing vulnerability in the NodeRequestUrl (which extends FastURL) which allows middleware bypass. When event.url, event.url.hostname, or event…

EPSS: 0.000 (10.5th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.4 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

H3js H3 — versions >= 2.0.0-0, < 2.0.1-rc.15

Weakness classification (CWE)

CWE-290 — Authentication Bypass by Spoofing

References

https://github.com/h3js/h3/security/advisories/GHSA-3vj8-jmxq-cgj5 (x_refsource_CONFIRM)

Frequently asked questions

What is CVE-2026-33131?: CVE-2026-33131 is a high-severity vulnerability in H3js H3, classified under Authentication Bypass by Spoofing. CVSS score: 7.4/10. Published 2026-03-20.
How severe is CVE-2026-33131?: High severity. CVSS v3 base score is 7.4 out of 10.