The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util…
Priority HIGH 65CWE-776Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA and Red Hat.
Summary
The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util before 1.3.7, as used in the mod_dav and mod_dav_svn modules in the Apache HTTP Server, allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document containing a large number of nested entity references, as demonstrated by a PROPFIND request, a similar issue to CVE-2003-1564.
Why it matters now
EPSS 0.52988 98th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by the CNA and NVD
Fix Fixed Red Hat: 4 advisories
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 13
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:apache:apr-util:*:*:*:*:*:*:*:* | before 1.3.7 | Vulnerable | Apache |
| cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:* | before 10.6.2 | Vulnerable | Apple |
| cpe:2.3:o:suse:linux_enterprise_server:9:*:*:*:*:*:*:* | 9 | Vulnerable | SUSE |
| cpe:2.3:o:debian:debian_linux:4.0:*:*:*:*:*:*:* | 4.0 | Vulnerable | Debian |
| cpe:2.3:o:canonical:ubuntu_linux:6.06:*:*:*:*:*:*:* | 6.06 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:8.04:*:*:*:-:*:*:* | 8.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:8.10:*:*:*:*:*:*:* | 8.10 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:9.04:*:*:*:*:*:*:* | 9.04 | Vulnerable | Canonical |
| cpe:2.3:o:fedoraproject:fedora:9:*:*:*:*:*:*:* | 9 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:10:*:*:*:*:*:*:* | 10 | Vulnerable | Fedoraproject |
- cpe:2.3:a:apache:apr-util:*:*:*:*:*:*:*:* Versions before 1.3.7 Vulnerable ·Apache
- cpe:2.3:o:apple:mac_os_x:*:*:*:*:*:*:*:* Versions before 10.6.2 Vulnerable ·Apple
- cpe:2.3:o:suse:linux_enterprise_server:9:*:*:*:*:*:*:* Versions 9 Vulnerable ·SUSE
- cpe:2.3:o:debian:debian_linux:4.0:*:*:*:*:*:*:* Versions 4.0 Vulnerable ·Debian
- cpe:2.3:o:canonical:ubuntu_linux:6.06:*:*:*:*:*:*:* Versions 6.06 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:8.04:*:*:*:-:*:*:* Versions 8.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:8.10:*:*:*:*:*:*:* Versions 8.10 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:9.04:*:*:*:*:*:*:* Versions 9.04 Vulnerable ·Canonical
- cpe:2.3:o:fedoraproject:fedora:9:*:*:*:*:*:*:* Versions 9 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:10:*:*:*:*:*:*:* Versions 10 Vulnerable ·Fedoraproject
Show 3 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:fedoraproject:fedora:11:*:*:*:*:*:*:* | 11 | Vulnerable | Fedoraproject |
| cpe:2.3:a:oracle:http_server:-:*:*:*:*:*:*:* | not specified by NVD | Vulnerable | Oracle |
| cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* | 2.2.0 to before 2.2.12 | Vulnerable | Apache |
- cpe:2.3:o:fedoraproject:fedora:11:*:*:*:*:*:*:* Versions 11 Vulnerable ·Fedoraproject
- cpe:2.3:a:oracle:http_server:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Oracle
- cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:* Versions 2.2.0 to before 2.2.12 Vulnerable ·Apache
Remediation
Red Hat 4 advisories
- RHSA-2010:0602 Released 2010-08-04 · Red Hat rating ModerateRed Hat Certificate System 7.3 security update
- Red Hat Certificate System 7.3 for 4AS ant-1.6.5-1jpp_1rh, avalon-logkit-1.2-2jpp_4rh, axis-1.2.1-1jpp_3rh +39
- Red Hat Certificate System 7.3 for 4ES ant-1.6.5-1jpp_1rh, avalon-logkit-1.2-2jpp_4rh, axis-1.2.1-1jpp_3rh +39
- RHSA-2009:1160 Released 2009-07-17 · Red Hat rating Importanthttpd22 security update
- Red Hat JBoss Web Server 1.0 for RHEL 4 AS httpd22-2.2.10-23.1.ep5.el4, httpd22-2.2.10-23.1.ep5.el4.i386, httpd22-apr-2.2.10-23.1.ep5.el4 +11
- Red Hat JBoss Web Server 1.0 for RHEL 4 ES httpd22-2.2.10-23.1.ep5.el4, httpd22-2.2.10-23.1.ep5.el4.i386, httpd22-apr-2.2.10-23.1.ep5.el4 +11
- RHSA-2009:1108 Released 2009-06-16 · Red Hat rating Moderatehttpd security update
- Red Hat Desktop version 3 httpd-2.0.46-73.ent, httpd-2.0.46-73.ent.i386, httpd-devel-2.0.46-73.ent +3
- Red Hat Enterprise Linux AS version 3 httpd-2.0.46-73.ent, httpd-2.0.46-73.ent.i386, httpd-2.0.46-73.ent.ia64 +9
- Red Hat Enterprise Linux ES version 3 httpd-2.0.46-73.ent, httpd-2.0.46-73.ent.i386, httpd-2.0.46-73.ent.ia64 +6
- Red Hat Enterprise Linux WS version 3 httpd-2.0.46-73.ent, httpd-2.0.46-73.ent.i386, httpd-2.0.46-73.ent.ia64 +6
Show 1 more Red Hat advisories
- RHSA-2009:1107 Released 2009-06-16 · Red Hat rating Moderateapr-util security update
- Red Hat Enterprise Linux (v. 5 server) apr-util-1.2.7-7.el5_3.1, apr-util-1.2.7-7.el5_3.1.i386, apr-util-1.2.7-7.el5_3.1.ia64 +9
- Red Hat Enterprise Linux AS version 4 apr-util-0.9.4-22.el4_8.1, apr-util-0.9.4-22.el4_8.1.i386, apr-util-0.9.4-22.el4_8.1.ia64 +5
- Red Hat Enterprise Linux Desktop (v. 5 client) apr-util-1.2.7-7.el5_3.1, apr-util-1.2.7-7.el5_3.1.i386, apr-util-docs-1.2.7-7.el5_3.1 +1
- Red Hat Enterprise Linux Desktop Workstation (v. 5 client) apr-util-1.2.7-7.el5_3.1, apr-util-devel-1.2.7-7.el5_3.1, apr-util-devel-1.2.7-7.el5_3.1.i386
- Red Hat Enterprise Linux Desktop version 4 apr-util-0.9.4-22.el4_8.1, apr-util-0.9.4-22.el4_8.1.i386, apr-util-devel-0.9.4-22.el4_8.1 +1
- Red Hat Enterprise Linux ES version 4 apr-util-0.9.4-22.el4_8.1, apr-util-0.9.4-22.el4_8.1.i386, apr-util-0.9.4-22.el4_8.1.ia64 +3
- Red Hat Enterprise Linux WS version 4 apr-util-0.9.4-22.el4_8.1, apr-util-0.9.4-22.el4_8.1.i386, apr-util-0.9.4-22.el4_8.1.ia64 +3
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Certificate System 7.3 for 4AS | Fixed | RHSA-2010:0602 |
| Red Hat Certificate System 7.3 for 4ES | Fixed | RHSA-2010:0602 |
| Red Hat Desktop version 3 | Fixed | RHSA-2009:1108 |
| Red Hat Enterprise Linux (v. 5 server) | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux AS version 3 | Fixed | RHSA-2009:1108 |
| Red Hat Enterprise Linux AS version 4 | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux Desktop (v. 5 client) | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux Desktop Workstation (v. 5 client) | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux Desktop version 4 | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux ES version 3 | Fixed | RHSA-2009:1108 |
| Red Hat Enterprise Linux ES version 4 | Fixed | RHSA-2009:1107 |
| Red Hat Enterprise Linux WS version 3 | Fixed | RHSA-2009:1108 |
| Red Hat Enterprise Linux WS version 4 | Fixed | RHSA-2009:1107 |
| Red Hat JBoss Web Server 1.0 for RHEL 4 AS | Fixed | RHSA-2009:1160 |
| Red Hat JBoss Web Server 1.0 for RHEL 4 ES | Fixed | RHSA-2009:1160 |
Timeline
- 2026-10-02 Threatist record created from CVE-2009-1955
- 2026-10-03 Alias added: GHSA-hfr6-pxvf-frf7
References
Exploit 1
Patch 17
- [apr-dev] 20090602 [PATCH] prevent "billion laughs" attack against expat
- http://www.oracle.com/technetwork/topics/security/cpuapr2013-1899555.html
- http://svn.apache.org/viewvc?view=rev&revision=781403
- [httpd-cvs] 20190815 svn commit: r1048743 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20190815 svn commit: r1048742 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20200401 svn commit: r1058586 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20200401 svn commit: r1058587 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/vulnerabilities-httpd.xml security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20210330 svn commit: r1073139 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/json/
- [httpd-cvs] 20210330 svn commit: r1888194 [6/13] - /httpd/site/trunk/content/security/json/
- [httpd-cvs] 20210330 svn commit: r1073140 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20210330 svn commit: r1073139 [6/13] - in /websites/staging/httpd/trunk/content: ./ security/json/
- [httpd-cvs] 20210330 svn commit: r1073146 [2/3] - in /websites/staging/httpd/trunk/content: ./ security/cvejsontohtml.py security/vulnerabilities-httpd.xml security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20210330 svn commit: r1073149 [1/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/
- [httpd-cvs] 20210330 svn commit: r1073149 [6/13] - in /websites/staging/httpd/trunk/content: ./ security/ security/json/
- [httpd-cvs] 20210603 svn commit: r1075360 [2/3] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20210606 svn commit: r1075467 [2/2] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2021-31618.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
- [httpd-cvs] 20210606 svn commit: r1075470 [3/4] - in /websites/staging/httpd/trunk/content: ./ security/json/CVE-2020-13938.json security/vulnerabilities_13.html security/vulnerabilities_20.html security/vulnerabilities_22.html security/vulnerabilities_24.html
Advisory 24
- DSA-1812
- ADV-2009-1907
- FEDORA-2009-5969
- MDVSA-2009:131
- oval:org.mitre.oval:def:10270
- ADV-2010-1107
- PK99478
- SUSE-SR:2010:011
- PK91241
- PK88342
- FEDORA-2009-6014
- RHSA-2009:1108
- HPSBUX02612
- oval:org.mitre.oval:def:12473
- GLSA-200907-03
- FEDORA-2009-6261
- USN-786-1
- ADV-2009-3184
- SSA:2009-167-02
- http://www-01.ibm.com/support/docview.wss?uid=swg27014463
- APPLE-SA-2009-11-09-1
- MDVSA-2013:150
- RHSA-2009:1107
- USN-787-1
Sources
- CVE-2009-1955 · CVE Program
- CVE-2009-1955 · NVD
- FIRST EPSS
- GHSA-hfr6-pxvf-frf7 · GitHub Advisory Database · CC BY 4.0
- CVE-2009-1955 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences