CVE-2020-17525Network attack vector

HTTPD crash via unchecked repository root pointer

Published Mar 17, 2021 · Updated Feb 13, 2025

NULL pointer dereference in Apache Subversion mod_authz_svn allows remote attackers to crash HTTPD via a GET for a nonexistent repository. In get_repos_config, svn_repos_find_root_path returns NULL for the missing on-disk repository, but the result is passed to svn_repos_open3 without a NULL check. The server is exposed only when mod_dav_svn and mod_authz_svn use an in-repository authz file; the crash kills a worker or the entire HTTPD process, depending on the MPM.

CVSS severity7.5
High
EPSS probability40.08%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Apache Subversion mod_authz_svn allows remote attackers to crash HTTPD via a GET for a nonexistent repository. In get_repos_config, svn_repos_find_root_path returns NULL for the missing on-disk repository, but the result is passed to svn_repos_open3 without a NULL check. The server is exposed only when mod_dav_svn and mod_authz_svn use an in-repository authz file; the crash kills a worker or the entire HTTPD process, depending on the MPM.

The record

CVE
CVE-2020-17525
Published
Mar 17, 2021
Updated
Feb 13, 2025
Vendor
The Apache Software Foundation
Product
Apache Subversion
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record 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=mod_authz_svn <1.14.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Subversionversion=mod_authz_svn <1.14.1

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/A:P
7.5Apache Software FoundationCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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-476NULL Pointer Dereference
T1499.004Application or System Exploitation

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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