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NVD Vulnerability Details :
CVE-2026-40023
Analyzed
More InfoOfficial Page
Source-security@apache.org
View Known Exploited Vulnerability (KEV) details
Published At-10 Apr, 2026 | 16:16
Updated At-21 Apr, 2026 | 14:49

Apache Log4cxx's XMLLayout https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html , in versions before 1.7.0, fails to sanitize characters forbidden by the XML 1.0 specification https://www.w3.org/TR/xml/#charsets in log messages, NDC, and MDC property keys and values, producing invalid XML output. Conforming XML parsers must reject such documents with a fatal error, which may cause downstream log processing systems to drop or fail to index affected records. An attacker who can influence logged data can exploit this to suppress individual log records, impairing audit trails and detection of malicious activity. Users are advised to upgrade to Apache Log4cxx 1.7.0, which fixes this issue.

CISA Catalog
Date AddedDue DateVulnerability NameRequired Action
N/A
Date Added: N/A
Due Date: N/A
Vulnerability Name: N/A
Required Action: N/A
Metrics
TypeVersionBase scoreBase severityVector
Secondary4.06.3MEDIUM
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Primary3.15.3MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Type: Secondary
Version: 4.0
Base score: 6.3
Base severity: MEDIUM
Vector:
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Type: Primary
Version: 3.1
Base score: 5.3
Base severity: MEDIUM
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CPE Matches
The Apache Software Foundation
apache
>>log4cxx>>Versions before 1.7.0(exclusive)
cpe:2.3:a:apache:log4cxx:*:*:*:*:*:*:*:*
Weaknesses
CWE IDTypeSource
CWE-116Secondarysecurity@apache.org
CWE ID: CWE-116
Type: Secondary
Source: security@apache.org
Evaluator Description
Evaluator Impact

Evaluator Solution

Vendor Statements
References
HyperlinkSourceResource
https://github.com/apache/logging-log4cxx/pull/609security@apache.org
Issue Tracking
Patch
https://lists.apache.org/thread/y15cv3zblg3dfwr5vy6ddbnl4zyrzr8bsecurity@apache.org
Mailing List
Vendor Advisory
https://logging.apache.org/cyclonedx/vdr.xmlsecurity@apache.org
Product
https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.htmlsecurity@apache.org
Product
https://logging.apache.org/security.html#CVE-2026-40023security@apache.org
Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/04/10/12af854a3a-2127-422b-91ae-364da2661108
Mailing List
Third Party Advisory
Hyperlink: https://github.com/apache/logging-log4cxx/pull/609
Source: security@apache.org
Resource:
Issue Tracking
Patch
Hyperlink: https://lists.apache.org/thread/y15cv3zblg3dfwr5vy6ddbnl4zyrzr8b
Source: security@apache.org
Resource:
Mailing List
Vendor Advisory
Hyperlink: https://logging.apache.org/cyclonedx/vdr.xml
Source: security@apache.org
Resource:
Product
Hyperlink: https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.html
Source: security@apache.org
Resource:
Product
Hyperlink: https://logging.apache.org/security.html#CVE-2026-40023
Source: security@apache.org
Resource:
Vendor Advisory
Hyperlink: http://www.openwall.com/lists/oss-security/2026/04/10/12
Source: af854a3a-2127-422b-91ae-364da2661108
Resource:
Mailing List
Third Party Advisory
Change History
0Changes found
Details not found