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Vulnerability record · CVE-2022-30780 · published 11 June 2022

CVE-2022-30780: Lighttpd header parsing typo enables remote denial of service

Lighttpd · Lighttpd

Lighttpd 1.4.56 through 1.4.58 contains a typo in connection_read_header_more in connections.c that disrupts multiple read operations on large headers. A remote attacker can send crafted large headers to consume CPU through stuck connections, causing a denial of service. The flaw is a coding error (CWE-682) in the affected versions only.

7.5 CVSS 3.1 High EPSS 57% · top 1.0% CWE-682 · CWE-682
7.5CVSS 3.1 base score, v2 5.0
57%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
8References, 4 tagged exploit
17 Jun 2026Last modified by NVD

Description

Lighttpd 1.4.56 through 1.4.58 allows a remote attacker to cause a denial of service (CPU consumption from stuck connections) because connection_read_header_more in connections.c has a typo that disrupts use of multiple read operations on large headers.

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

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: high.

high priorityCVSS 7.5 availability-only flaw with public exploit code and very high EPSS (99th percentile), though not in KEV and requiring no authentication.

What it is

Lighttpd 1.4.56 through 1.4.58 contains a typo in connection_read_header_more in connections.c that disrupts multiple read operations on large headers. A remote attacker can send crafted large headers to consume CPU through stuck connections, causing a denial of service. The flaw is a coding error (CWE-682) in the affected versions only.

Impact

An unauthenticated remote attacker can exhaust server CPU and hold connections open, degrading or denying service to legitimate users. There is no confidentiality or integrity impact; only availability is affected.

Attack surface

Reachable over the network via HTTP requests with large headers; no authentication or user interaction is required per the CVSS vector AV:N/AC:L/PR:N/UI:N. Any internet-exposed or internal lighttpd 1.4.56-1.4.58 listener is a candidate.

Exploitation

Not listed in CISA KEV, but public exploit code exists per reference tags (Exploit) and EPSS is high at 0.5692 (99th percentile), indicating elevated likelihood of exploitation attempts.

What to do

  • Upgrade lighttpd to a version after 1.4.58 that contains the fix referenced in the vendor issue tracker (redmine.lighttpd.net/issues/3059).
  • If immediate upgrade is not possible, restrict or rate-limit inbound HTTP connections and cap header sizes at a reverse proxy or load balancer.
  • Monitor and tune connection timeouts and worker limits to reduce the impact of stuck connections.
  • Apply vendor patch or backport from the lighttpd1.4 repository if running a packaged distribution build.

Detection

  • Monitor for spikes in CPU usage and long-lived or stuck HTTP connections on lighttpd hosts.
  • Alert on unusually large or malformed HTTP request headers reaching lighttpd.
  • Track connection counts and worker saturation per listener to spot sustained connection exhaustion patterns.
  • Review web server logs for repeated large-header requests from single sources.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/lighttpd/lighttpd1.4 ProductThird Party Advisory
https://github.com/p0dalirius/CVE-2022-30780-lighttpd-denial-of-service ExploitThird Party Advisory
https://podalirius.net/en/cves/2022-30780/ ExploitThird Party Advisory
https://redmine.lighttpd.net/issues/3059 Issue TrackingPatchVendor Advisory
https://github.com/lighttpd/lighttpd1.4 ProductThird Party Advisory
https://github.com/p0dalirius/CVE-2022-30780-lighttpd-denial-of-service ExploitThird Party Advisory
https://podalirius.net/en/cves/2022-30780/ ExploitThird Party Advisory
https://redmine.lighttpd.net/issues/3059 Issue TrackingPatchVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2022-30780), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.