CVE-2021-22959

Name: CVE-2021-22959
Creator: NVD / NIST
Published: 2021-11-15T15:15:06.747+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.5/10EPSS 2.94%

Last modified Jun 17, 2026

CVE-2021-22959 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. 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.. EPSS estimates a 2.94% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

6.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

EPSS Probability

2.94%

85.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Llhttp	Llhttp	< 2.1.4
Llhttp	Llhttp	>= 3.0.0, < 6.0.6
Oracle	Graalvm	20.3.4
Oracle	Graalvm	21.3.0
Debian	Debian Linux	11.0

References

https://hackerone.com/reports/1238709Exploit, Issue Tracking, Third Party Advisory
https://www.debian.org/security/2022/dsa-5170Mailing List, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://hackerone.com/reports/1238709Exploit, Issue Tracking, Third Party Advisory
https://www.debian.org/security/2022/dsa-5170Mailing List, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory

Timeline

Published: Nov 15, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is 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.

How severe is CVE-2021-22959?

CVE-2021-22959 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 2.94% probability of exploitation in the next 30 days.

How do I fix CVE-2021-22959?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-22959?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST