Dashboard / CVE-2026-40023

CVE-2026-40023

MEDIUM
MEDIUM Priority: 0.03 BB Relevance: 73/100
Published: 2026-04-10 Modified: 2026-10-26 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction

CVSS Vector Breakdown

AV: Network
AC: High
PR: None
UI: None
S: X
AT: None
VC: None
VI: None
VA: None

Description

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
apache log4cxx < 1.7.0

References & Advisories (6)

Bug Bounty Relevance

73 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity
✓ No user interaction

CVSS Score

6.3 / 10.0 v4.0
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

EPSS — Exploitation Probability

0.50%
Raw Score 0.004990
Percentile 42.7%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00499
2026-10-28
0.00499

Intelligence Sources

nvd ref →

External Links