What’s Vulnerable › Vulnerabilities

CVE-2021-22959

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.2% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-11-15 · updated 2026-06-17
• Weakness: CWE-444

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.

Affected products

• Debian Linux: 11.0
• Llhttp: before 2.1.4; from 3.0.0 before 6.0.6 — fixed in 2.1.4, 6.0.6
• Oracle Corporation GraalVM Enterprise Edition: 20.3.4, 21.3.0

How to fix

Upgrade to a fixed version: Llhttp 2.1.4, 6.0.6. Check the vendor advisory for mitigations.

References

• https://hackerone.com/reports/1238709
• https://www.debian.org/security/2022/dsa-5170
• https://www.oracle.com/security-alerts/cpujan2022.html
• https://hackerone.com/reports/1238709
• https://www.debian.org/security/2022/dsa-5170
• https://www.oracle.com/security-alerts/cpujan2022.html

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