CVE-2022-22721Network attack vector

Memory corruption via overflowing XML escape size

Published Mar 14, 2022 · Updated Aug 3, 2024

Integer overflow in Apache HTTP Server 2.4.52 and earlier allows remote attackers to corrupt memory via oversized XML request bodies. The ap_escape_html2 function used int counters while expanding XML body bytes, so a body above 350 MB on a 32-bit build can wrap the calculated output size and drive out-of-bounds writes. Exploitation requires LimitXMLRequestBody to be raised above 350 MB from its 1 MB default; the corruption can crash the service or alter execution.

CVSS severity9.1
Critical
EPSS probability41.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer overflow in Apache HTTP Server 2.4.52 and earlier allows remote attackers to corrupt memory via oversized XML request bodies. The ap_escape_html2 function used int counters while expanding XML body bytes, so a body above 350 MB on a 32-bit build can wrap the calculated output size and drive out-of-bounds writes. Exploitation requires LimitXMLRequestBody to be raised above 350 MB from its 1 MB default; the corruption can crash the service or alter execution.

The record

CVE
CVE-2022-22721
Published
Mar 14, 2022
Updated
Aug 3, 2024
Vendor
The Apache Software Foundation
Product
Apache HTTP Server
Classifications
CWE-190, CAPEC-92, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 14, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Apache HTTP Server 2.4 <=2.4.52

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache HTTP Serverversion=Apache HTTP Server 2.4 <=2.4.52

Published CVSS scores

7.4SUSECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:H
9.1CanonicalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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-190Integer Overflow or Wraparound
CAPEC-92Forced Integer Overflow
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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