From 1d9421b8b2d7b094fd3b04dbce25a726dc678f55 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Sun, 8 Mar 2020 10:55:19 -0400
Subject: [PATCH] Improve validation of CSS selector-based cosmetic filters

Reported internally. The following invalid filter was not
discarded by uBO:

    123tvnow.com##.123tv-ads

The correct form should be:

    123tvnow.com##.\31 23tv-ads

Not discarding invalid CSS selector-based cosmetic
filter may break CSS selector-based cosmetic
filtering.
---
 src/js/static-ext-filtering.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/js/static-ext-filtering.js b/src/js/static-ext-filtering.js
index 2de1e29f0..c855f3638 100644
--- a/src/js/static-ext-filtering.js
+++ b/src/js/static-ext-filtering.js
@@ -98,7 +98,7 @@
         }
         // Quick regex-based validation -- most cosmetic filters are of the
         // simple form and in such case a regex is much faster.
-        const reSimple = /^[#.][\w-]+$/;
+        const reSimple = /^[#.][A-Za-z_][\w-]*$/;
         return s => {
             if ( reSimple.test(s) ) { return 1; }
             const pos = cssPseudoSelector(s);