diff --git a/pyproject.toml b/pyproject.toml
index d8b00c0a..d75d3bf5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ dependencies = [
     "sse-starlette>=1.6.0",  # Server-Sent Events support
     "prometheus-client>=0.19.0",  # Prometheus metrics
     "psutil>=7.2.2",  # System resource monitoring for sprite worker
-    "Pillow>=10.0.0",  # Image processing for thumbnail uploads (security hardening)
+    "Pillow>=11.3.0",  # Image processing for thumbnail uploads (security hardening)
     "argon2-cffi>=23.1.0",  # Secure API key hashing (Issue #445)
     "email-validator>=2.0.0",  # Pydantic EmailStr validation (Issue #200)
     "authlib>=1.3.0",  # OIDC integration (Issue #200)
diff --git a/requirements.txt b/requirements.txt
index 258725de..4776ebc6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -27,7 +27,7 @@ slowapi>=0.1.9
 psutil>=5.9.0
 
 # Image processing for thumbnail uploads
-Pillow>=10.0.0
+Pillow>=11.3.0
 
 # HTML sanitization for comments
 bleach>=6.0.0