CVE-2022-41556

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 3.8% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2022-10-06 · updated 2026-06-17
Weakness: CWE-401

Description

A resource leak in gw_backend.c in lighttpd 1.4.56 through 1.4.66 could lead to a denial of service (connection-slot exhaustion) after a large amount of anomalous TCP behavior by clients. It is related to RDHUP mishandling in certain HTTP/1.1 chunked situations. Use of mod_fastcgi is, for example, affected. This is fixed in 1.4.67.

Affected products

Fedoraproject Fedora: 35
lighttpd: from 1.4.56 before 1.4.67 — fixed in 1.4.67

How to fix

Upgrade to a fixed version: lighttpd 1.4.67. Check the vendor advisory for mitigations.

References

https://git.lighttpd.net/lighttpd/lighttpd1.4/commit/b18de6f9264f914f7bf493abd3b6059343548e50
https://github.com/lighttpd/lighttpd1.4/compare/lighttpd-1.4.66...lighttpd-1.4.67
https://github.com/lighttpd/lighttpd1.4/pull/115
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OVOSBSCMLGCHH2Z74H64ZWVDFJFQTBC2/
https://security.gentoo.org/glsa/202210-12
https://git.lighttpd.net/lighttpd/lighttpd1.4/commit/b18de6f9264f914f7bf493abd3b6059343548e50
https://github.com/lighttpd/lighttpd1.4/compare/lighttpd-1.4.66...lighttpd-1.4.67
https://github.com/lighttpd/lighttpd1.4/pull/115
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OVOSBSCMLGCHH2Z74H64ZWVDFJFQTBC2/
https://security.gentoo.org/glsa/202210-12

Get alerted when CVE-2022-41556 or the next vulnerability affects your stack