diff --git a/src/Monolog/Processor/RedactSensitiveProcessor.php b/src/Monolog/Processor/RedactSensitiveProcessor.php
new file mode 100644
index 000000000..6b8225746
--- /dev/null
+++ b/src/Monolog/Processor/RedactSensitiveProcessor.php
@@ -0,0 +1,77 @@
+<?php
+declare(strict_types=1);
+
+namespace Monolog\Processor;
+
+use Monolog\LogRecord;
+
+final class RedactSensitiveProcessor implements ProcessorInterface
+{
+    /** @var string[] */
+    private array $sensitiveKeys;
+
+    /** @var string[] */
+    private array $patterns;
+
+    private string $mask;
+
+    /**
+     * @param string[] $sensitiveKeys exact keys to redact in context/extra (case-insensitive)
+     * @param string[] $patterns PCRE regex patterns to mask inside string values (e.g. '/Bearer\\s+[A-Za-z0-9\\._-]+/')
+     * @param string   $mask replacement token
+     */
+    public function __construct(array $sensitiveKeys = ['password','passwd','pwd','secret','token','api_key','apikey','authorization','auth','cookie'], array $patterns = [], string $mask = 'REDACTED')
+    {
+        $this->sensitiveKeys = array_map('strtolower', $sensitiveKeys);
+        $this->patterns = $patterns;
+        $this->mask = $mask;
+    }
+
+    public function __invoke(LogRecord $record): LogRecord
+    {
+        $context = $this->sanitize($record->context);
+        $extra   = $this->sanitize($record->extra);
+
+        $message = $record->message;
+        foreach ($this->patterns as $pattern) {
+            if (@preg_match($pattern, '') === false) {
+                continue; // ignore invalid pattern instead of throwing inside logging path
+            }
+            $message = preg_replace($pattern, $this->mask, $message) ?? $message;
+        }
+
+        return $record->with(
+            message: $message,
+            context: $context,
+            extra: $extra
+        );
+    }
+
+    /** @param mixed $value */
+    private function sanitize(mixed $value): mixed
+    {
+        if (is_array($value)) {
+            $sanitized = [];
+            foreach ($value as $k => $v) {
+                $key = \is_string($k) ? strtolower($k) : $k;
+                if (is_string($k) && in_array($key, $this->sensitiveKeys, true)) {
+                    $sanitized[$k] = $this->mask;
+                } else {
+                    $sanitized[$k] = $this->sanitize($v);
+                }
+            }
+            return $sanitized;
+        }
+
+        if (is_string($value) && $this->patterns) {
+            foreach ($this->patterns as $pattern) {
+                if (@preg_match($pattern, '') === false) {
+                    continue;
+                }
+                $value = preg_replace($pattern, $this->mask, $value) ?? $value;
+            }
+        }
+
+        return $value;
+    }
+}
diff --git a/tests/Monolog/Processor/RedactSensitiveProcessorTest.php b/tests/Monolog/Processor/RedactSensitiveProcessorTest.php
new file mode 100644
index 000000000..2e6a388da
--- /dev/null
+++ b/tests/Monolog/Processor/RedactSensitiveProcessorTest.php
@@ -0,0 +1,58 @@
+<?php
+declare(strict_types=1);
+
+namespace Monolog\Processor;
+
+use Monolog\Level;
+use Monolog\LogRecord;
+use PHPUnit\Framework\TestCase;
+
+final class RedactSensitiveProcessorTest extends TestCase
+{
+    public function testRedactsContextAndExtraKeys(): void
+    {
+        $p = new RedactSensitiveProcessor();
+
+        $rec = new LogRecord(
+            datetime: new \DateTimeImmutable('@0'),
+            channel: 'test',
+            level: Level::Info,
+            message: 'Login for {user}',
+            context: ['user' => 'rishi', 'password' => 'super-secret', 'nested' => ['api_key' => 'abc123']],
+            extra: ['token' => 't-456', 'irrelevant' => 'keep']
+        );
+
+        $out = $p($rec);
+
+        $this->assertSame('REDACTED', $out->context['password']);
+        $this->assertSame('REDACTED', $out->context['nested']['api_key']);
+        $this->assertSame('REDACTED', $out->extra['token']);
+        $this->assertSame('keep', $out->extra['irrelevant']);
+    }
+
+    public function testRedactsWithPatterns(): void
+    {
+        $p = new RedactSensitiveProcessor(
+            sensitiveKeys: [],
+            patterns: ['/(Bearer\\s+)[A-Za-z0-9\\._-]+/i', '/([\\w.%+-]+@[\\w.-]+\\.[A-Za-z]{2,})/']
+        );
+
+        $rec = new LogRecord(
+            new \DateTimeImmutable('@0'), 'test', Level::Info,
+            'Auth {h}: Bearer abc.def-ghi and user john@example.com',
+            ['h' => 'header'], []
+        );
+
+        $out = $p($rec);
+        $this->assertSame('Auth {h}: REDACTED and user REDACTED', $out->message);
+    }
+
+    public function testIgnoresInvalidRegexSafely(): void
+    {
+        $p = new RedactSensitiveProcessor([], ['/[invalid/']);
+        $rec = new LogRecord(new \DateTimeImmutable('@0'), 'test', Level::Info, 'hello', [], []);
+        $out = $p($rec);
+        $this->assertSame('hello', $out->message);
+    }
+}
+?>
\ No newline at end of file