CVE•Published 2026-10-06•Modified 2026-10-09•0 articles on news•3 live references•NVD data

CVE-2026-105242Apache · Log4net

Vulnerability data via NVD (ingested)

CVSS v3.1

5.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS percentile

Exploit Prediction Scoring System · top 75% of all CVEs

Weaknesses (CWE)

CWE-755Improper Handling of Exceptional Conditions

Description

Improper Handling of Exceptional Conditions vulnerability in the aspnet-request pattern converter of Apache log4net. Reading request parameters triggers ASP.NET request validation, so a request carrying content such as markup made the layout throw and the appender discarded the whole event. A sender could suppress the log record of their own request. Only applications on ASP.NET for .NET Framework whose layout uses %aspnet-request are affected. This issue affects Apache log4net: from 1.2.11 before 3.5.0. Users are recommended to upgrade to version 3.5.0, which fixes the issue.

Timeline

Published 2026-10-06

Modified 2026-10-09

External references

NVD MITRE VulnCheck

Search for exposed instances

Shodan + Censys queries derived from NVD's CPE data. The vuln tag catches assets Shodan has explicitly linked to this CVE; the product / banner fingerprints find exposed instances even when the vuln tag was never applied (which is common).

Shodan · vuln tag0 hosts

vuln:CVE-2026-105242

Hosts Shodan has explicitly fingerprinted as vulnerable.

Shodan · product

product:"Apache Log4net"

All exposed Apache Log4net instances — cross-reference with the CVE's affected-version range.

Shodan · banner/body mention

http.html:"Log4net"

HTTP body or banner mentions "Log4net" — catches deploys Shodan didn't identify as a product.

More intel sources (5)

Shodan report

vuln:CVE-2026-105242