CVE-2022-41556Network attack vector

Service interruption via unreleased chunked-request connections

Published Oct 6, 2022 · Updated Aug 3, 2024

Resource leak in lighttpd 1.4.56 through 1.4.66 allows remote attackers to exhaust connection slots via aborted chunked requests. In gw_backend.c, gw_handle_subrequest returns HANDLER_WAIT_FOR_EVENT instead of propagating the RDHUP read result when a nonstreamed HTTP/1.1 chunked body ends early, leaving the socket stuck in CLOSE_WAIT. A gateway backend such as mod_fastcgi must be used without request-body streaming, and repeated anomalous TCP sessions interrupt service after the connection limit is reached.

CVSS severity7.5
High
EPSS probability2.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource leak in lighttpd 1.4.56 through 1.4.66 allows remote attackers to exhaust connection slots via aborted chunked requests. In gw_backend.c, gw_handle_subrequest returns HANDLER_WAIT_FOR_EVENT instead of propagating the RDHUP read result when a nonstreamed HTTP/1.1 chunked body ends early, leaving the socket stuck in CLOSE_WAIT. A gateway backend such as mod_fastcgi must be used without request-body streaming, and repeated anomalous TCP sessions interrupt service after the connection limit is reached.

The record

CVE
CVE-2022-41556
Published
Oct 6, 2022
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-401, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 6, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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