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CVE-2006-0743 — log4net

Fix: apache/logging-log4net@ea3faab

CVE-2006-0743 is a CWE-134 vulnerability in log4net. A fix is available for log4net — see the affected versions and patch details below.

Apache log4net format string vulnerability causes DoS

Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
6.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs94th percentile — riskier than 94% of all scored CVEsHighest risk
3.90%4.91%5.93%6.94%4.5%6.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
.NETlog4net

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.

Description

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
.NETNuGetlog4netall versions1.2.10dotnet add package log4net --version 1.2.10

Affected Products

1 product · 1 configurations
Application
log4netapache
1 version
1.2.9_beta

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for log4net, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update log4net to 1.2.10 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2006-0743 is resolved across your whole dependency graph.

  3. Workarounds

    Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

Format string vulnerability in LocalSyslogAppender in Apache log4net 1.2.9 might allow remote attackers to cause a denial of service (memory corruption and termination) via unknown vectors.
O3 Security · Impact-Aware SCA

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CVE-2006-0743: log4net DoS — Fixed in 1.2.10