(logging-log4net) branch Feature/AVSS-Fixes updated: Fix unhandled exception in AppenderSkeleton finalizer isking process termination Wrap Close() in the finalizer with try-catch for non-fatal exceptions and move _isClosed into a finally block to prevent repeated finalization attempts (CWE-755)

[freeandnil]

This is an automated email from the ASF dual-hosted git repository.

FreeAndNil pushed a commit to branch Feature/AVSS-Fixes
in repository https://gitbox.apache.org/repos/asf/logging-log4net.git


The following commit(s) were added to refs/heads/Feature/AVSS-Fixes by this 
push:
     new 3113aa8a Fix unhandled exception in AppenderSkeleton finalizer isking 
process termination Wrap Close() in the finalizer with try-catch for non-fatal 
exceptions and move _isClosed into a finally block to prevent repeated 
finalization attempts (CWE-755)
3113aa8a is described below

commit 3113aa8aee472edb7de73bf066d5a56c494ba520
Author: Jan Friedrich <freeand...@apache.org>
AuthorDate: Sun Jun 21 23:37:17 2026 +0200

    Fix unhandled exception in AppenderSkeleton finalizer isking process 
termination
    Wrap Close() in the finalizer with try-catch for non-fatal exceptions and 
move _isClosed into a finally block to prevent repeated finalization attempts 
(CWE-755)
---
 ...8-fix-appender-skeleton-finalizer-exception.xml | 11 ++++++++++
 src/log4net/Appender/AppenderSkeleton.cs           | 24 +++++++++++++++++-----
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git 
a/src/changelog/3.3.2/298-fix-appender-skeleton-finalizer-exception.xml 
b/src/changelog/3.3.2/298-fix-appender-skeleton-finalizer-exception.xml
new file mode 100644
index 00000000..f12ef5c4
--- /dev/null
+++ b/src/changelog/3.3.2/298-fix-appender-skeleton-finalizer-exception.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+       xmlns="https://logging.apache.org/xml/ns";
+       xsi:schemaLocation="https://logging.apache.org/xml/ns 
https://logging.apache.org/xml/ns/log4j-changelog-0.xsd";
+       type="fixed">
+  <issue id="f57d7b3-003" 
link="https://github.com/apache/tooling-agents/blob/main/ASVS/reports/logging-log4net/f57d7b3/issues.md#issue-finding-003---finalizer-path-lacks-exception-protection-risking-process-termination"/>
+  <issue id="298" link="https://github.com/apache/logging-log4net/pull/298"/>
+  <description format="asciidoc">
+    fix unhandled exception in `AppenderSkeleton` finalizer that could 
terminate the process when `OnClose()` throws (CWE-755)
+  </description>
+</entry>
diff --git a/src/log4net/Appender/AppenderSkeleton.cs 
b/src/log4net/Appender/AppenderSkeleton.cs
index 6fb3ab3a..adf34128 100644
--- a/src/log4net/Appender/AppenderSkeleton.cs
+++ b/src/log4net/Appender/AppenderSkeleton.cs
@@ -65,13 +65,21 @@ public abstract class AppenderSkeleton : IAppender, 
IBulkAppender, IOptionHandle
   /// </remarks>
   ~AppenderSkeleton()
   {
-    // An appender might be closed then garbage collected. 
+    // An appender might be closed then garbage collected.
     // There is no point in closing twice.
-    if (!_isClosed)
+    if (_isClosed)
+    {
+      return;
+    }
+    LogLog.Debug(_declaringType, $"Finalizing appender named [{Name}].");
+    try
     {
-      LogLog.Debug(_declaringType, $"Finalizing appender named [{Name}].");
       Close();
     }
+    catch (Exception ex) when (!ex.IsFatal())
+    {
+      LogLog.Warn(_declaringType, $"Exception during finalization of 
{GetType().FullName} [{Name}].", ex);
+    }
   }
 
   /// <summary>
@@ -198,8 +206,14 @@ public void Close()
     {
       if (!_isClosed)
       {
-        OnClose();
-        _isClosed = true;
+        try
+        {
+          OnClose();
+        }
+        finally
+        {
+          _isClosed = true;
+        }
       }
     }
   }