From fac3ea77d8d86a0835926eb8f422a552ca83db2a Mon Sep 17 00:00:00 2001
From: Quentin Ligier <quentin.ligier@bluewin.ch>
Date: Fri, 1 Nov 2024 20:25:27 +0100
Subject: [PATCH] LibWeb: Fail the parsing of an invalid HSL legacy syntax

---
 Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index cc5dc002769..64a304b9f1f 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -2861,6 +2861,9 @@ RefPtr<CSSStyleValue> Parser::parse_hsl_color_value(TokenStream<ComponentValue>&
             inner_tokens.discard_whitespace();
 
             alpha = parse_number_percentage_value(inner_tokens);
+            // The parser has consumed a comma, so the alpha value is now required
+            if (!alpha)
+                return {};
             inner_tokens.discard_whitespace();
 
             if (inner_tokens.has_next_token())