Vulnerability in Llhttp

CVE-2021-22959

The parser in accepts requests with a space (SP) right after the header name before the colon. This can lead to HTTP Request Smuggling (HRS) in llhttp < v2.1.4 and < v6.0.6.

Vulnerability class: HTTP Request Smuggling

EPSS: 0.029 (85.7th percentile) — read the EPSS interpretation.

CVSS v3 metric

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

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2021-22959?
CVE-2021-22959 is a medium-severity vulnerability in Llhttp, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 6.5/10. Published 2021-11-15.
How severe is CVE-2021-22959?
Medium severity. CVSS v3 base score is 6.5 out of 10.