log4net Known Vulnerabilities & Fixes
log4net has 2 known security vulnerabilities in NuGet (.NET). Upgrade to version 3.3.0 or later to resolve all known issues. Data sourced from OSV, enriched with EPSS exploit probability and CISA KEV.
Low Immediate Risk
No actively exploited vulnerabilities detected. Monitor and update in your next maintenance window.
Recommended safe version: 3.3.0
Upgrading to 3.3.0 or later resolves all 2 known vulnerabilities in log4net. Run: dotnet add package log4net --version 3.3.0
Is log4net in your project?
Check if you're affected and upgrade to 3.3.0 to stay secure.
Security Summary
- 2 affected version ranges have been identified across these 2 advisories.
- 100% of known issues have a published fixed version.
- Remediation: dotnet add package log4net
Vulnerabilities
2 unique vulnerabilities — sorted by exploitation risk (KEV → EPSS → CVSS). Click a CVE/GHSA ID for full details. First disclosed Jan 29, 2021, most recently Apr 10, 2026 (1897 days apart).
| CVE / GHSA | Severity | Affected | Fixed In |
|---|---|---|---|
| CVE-2018-1285 XML External Entity attack in log4net | CRITICAL | 1.2.10, 1.2.11, 2.0.0, 2.0.1 (+8 more) | 2.0.10 |
| CVE-2026-40021 Apache Log4net: Silent log event loss in XmlLayout and XmlLayoutSchemaLog4J due to unescaped XML 1.0 forbidden characters | MEDIUM | 1.2.10, 1.2.11, 2.0.0, 2.0.1 (+23 more) | 3.3.0 |
About This Data
Vulnerability data for log4net is sourced from the Open Source Vulnerability (OSV) database, aggregating reports from GitHub Advisory Database, NIST NVD, and ecosystem-specific sources.
CVSS (Common Vulnerability Scoring System) scores reflect exploitability and impact. EPSS (Exploit Prediction Scoring System) scores indicate the probability of exploitation within the next 30 days. Vulnerabilities marked with are listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.
Related NuGet (.NET) Packages
Other packages in this ecosystem, ranked by shared vulnerabilities where available.
Check Your Dependencies
Scan your project to check if you're using a vulnerable version of log4net.