diff --git a/pkg/workflow/argument_injection_test.go b/pkg/workflow/argument_injection_test.go
index e77bb8bfac0..3dfec340e2a 100644
--- a/pkg/workflow/argument_injection_test.go
+++ b/pkg/workflow/argument_injection_test.go
@@ -395,3 +395,34 @@ func TestValidatePipPackageName(t *testing.T) {
 		})
 	}
 }
+
+// TestValidateUvPackages_RejectsInvalidPackageName verifies that uv package names
+// which do not conform to the PyPI naming rules are rejected before being passed
+// as arguments to the uv CLI. This validation happens before uv/pip is resolved
+// or invoked, so the test is deterministic regardless of whether uv is installed
+// on the host running the test.
+func TestValidateUvPackages_RejectsInvalidPackageName(t *testing.T) {
+	compiler := NewCompiler()
+	err := compiler.validateUvPackages(&WorkflowData{
+		CustomSteps: "uvx pkg;whoami",
+	})
+	if err == nil {
+		t.Fatal("expected error for invalid uv package name but got none")
+	}
+	if !strings.Contains(err.Error(), "invalid pip package name") {
+		t.Errorf("expected error to mention invalid package name, got: %v", err)
+	}
+}
+
+// TestValidateUvPackages_AcceptsVersionedUvxSpec verifies that versioned uvx
+// package specs (e.g. "ruff@0.1.0") are not rejected by the PEP 508 name
+// validation, since extractUvFromCommands explicitly supports this syntax.
+func TestValidateUvPackages_AcceptsVersionedUvxSpec(t *testing.T) {
+	compiler := NewCompiler()
+	err := compiler.validateUvPackages(&WorkflowData{
+		CustomSteps: "uvx ruff@0.1.0",
+	})
+	if err != nil && strings.Contains(err.Error(), "invalid pip package name") {
+		t.Errorf("expected versioned uvx spec to be accepted as a valid package name, got: %v", err)
+	}
+}
diff --git a/pkg/workflow/pip_validation.go b/pkg/workflow/pip_validation.go
index 318f62cdd97..0ce72bd6c16 100644
--- a/pkg/workflow/pip_validation.go
+++ b/pkg/workflow/pip_validation.go
@@ -56,11 +56,9 @@ func (c *Compiler) validatePythonPackagesWithPip(packages []string, packageType
 	pipValidationLog.Printf("Validating %d %s packages using %s", len(packages), packageType, pipPath)
 
 	for _, pkg := range packages {
-		// Extract package name without version specifier
-		pkgName := pkg
-		if eqIndex := strings.Index(pkg, "=="); eqIndex > 0 {
-			pkgName = pkg[:eqIndex]
-		}
+		// Extract package name without version specifier (pip-style "==version"
+		// or uvx-style "@version", e.g. "ruff@0.1.0").
+		pkgName := stripUvPackageVersion(pkg)
 
 		// Reject names starting with '-' to prevent argument injection
 		if strings.HasPrefix(pkgName, "-") {
@@ -130,6 +128,19 @@ func (c *Compiler) validatePipPackages(workflowData *WorkflowData) error {
 	return nil
 }
 
+// stripUvPackageVersion extracts the bare package name from a uv package spec,
+// stripping a trailing "==version" (pip-style) or "@version" (uvx-style, e.g.
+// "ruff@0.1.0") specifier if present.
+func stripUvPackageVersion(pkg string) string {
+	if eqIndex := strings.Index(pkg, "=="); eqIndex > 0 {
+		return pkg[:eqIndex]
+	}
+	if atIndex := strings.Index(pkg, "@"); atIndex > 0 {
+		return pkg[:atIndex]
+	}
+	return pkg
+}
+
 // validateUvPackages validates that uv packages are available
 func (c *Compiler) validateUvPackages(workflowData *WorkflowData) error {
 	packages := extractUvPackages(workflowData)
@@ -147,6 +158,27 @@ func (c *Compiler) validateUvPackages(workflowData *WorkflowData) error {
 		return err
 	}
 
+	// Validate package name syntax (PEP 508) upfront, before resolving or invoking
+	// uv/pip and independent of whether those tools are installed. This ensures
+	// argument-injection attempts (e.g. "pkg;whoami") are rejected even in
+	// environments without uv or pip available.
+	var invalidNameErrors []string
+	for _, pkg := range packages {
+		pkgName := stripUvPackageVersion(pkg)
+		if err := validatePipPackageName(pkgName); err != nil {
+			pipValidationLog.Printf("Invalid uv package name %s: %v", pkgName, err)
+			invalidNameErrors = append(invalidNameErrors, fmt.Sprintf("uv package '%s' is invalid: %v", pkg, err))
+		}
+	}
+	if len(invalidNameErrors) > 0 {
+		return NewValidationError(
+			"uv.packages",
+			fmt.Sprintf("%d package name(s) invalid", len(invalidNameErrors)),
+			"uv package name(s) do not conform to PyPI naming rules (PEP 508)",
+			"Package names must start and end with a letter or digit, with hyphens, underscores, or dots allowed inside (e.g. \"requests\" or \"my-package\"). Optionally followed by a \"==version\" or \"@version\" specifier.\n\nValidation details:\n"+strings.Join(invalidNameErrors, "\n"),
+		)
+	}
+
 	// Check if uv is available
 	uvPath, err := fileutil.ResolveExecutablePath("uv")
 	if err != nil {
@@ -180,15 +212,16 @@ func (c *Compiler) validateUvPackages(workflowData *WorkflowData) error {
 	pipValidationLog.Print("Using uv command for validation")
 
 	// Validate with uv
+	// Package names were already validated against PyPI naming rules (PEP 508) above,
+	// before this point, so pkgName below is safe to pass as a command argument.
 	var errors []string
 	for _, pkg := range packages {
-		// Extract package name without version specifier
-		pkgName := pkg
-		if eqIndex := strings.Index(pkg, "=="); eqIndex > 0 {
-			pkgName = pkg[:eqIndex]
-		}
+		pkgName := stripUvPackageVersion(pkg)
 
 		// Use uv pip show to check if package exists on PyPI
+		// #nosec G204 -- uvPath is resolved from the hardcoded executable name "uv" via
+		// fileutil.ResolveExecutablePath; pkgName is validated above by validatePipPackageName
+		// against the strict PyPI PEP 508 allowlist.
 		cmd := exec.Command(uvPath, "pip", "show", pkgName, "--no-cache")
 		_, err := cmd.CombinedOutput()