CVE-2026-40023Apache 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 specificati…
Updated under an hour ago ()
Does this affect you?
It affects apache log4cxx. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
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.
- CVSS
- 5.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- Weakness (CWE)
- CWE-116
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Jun 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
apache log4cxx apache:log4cxx | before 1.7.0 | NVD |
References
- https://github.com/apache/logging-log4cxx/pull/609issue-tracking, patch
- https://lists.apache.org/thread/y15cv3zblg3dfwr5vy6ddbnl4zyrzr8bmailing-list, vendor-advisory
- https://logging.apache.org/cyclonedx/vdr.xmlproduct
- https://logging.apache.org/log4cxx/1.7.0/classlog4cxx_1_1xml_1_1XMLLayout.htmlproduct
- https://logging.apache.org/security.html#CVE-2026-40023vendor-advisory
- http://www.openwall.com/lists/oss-security/2026/04/10/12mailing-list, third-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.