From 9d00bd01ce7fe4e4b0854801cbb0468502f5ff85 Mon Sep 17 00:00:00 2001
From: bashonly <bashonly@protonmail.com>
Date: Wed, 11 Jun 2025 02:32:42 -0500
Subject: [PATCH] [devalue] guard against Python negative indexing

Authored by: bashonly
---
 yt_dlp/utils/web/devalue.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/yt_dlp/utils/web/devalue.py b/yt_dlp/utils/web/devalue.py
index 570a0388e..dbde0b941 100644
--- a/yt_dlp/utils/web/devalue.py
+++ b/yt_dlp/utils/web/devalue.py
@@ -39,6 +39,8 @@ def parse_iter(parsed: typing.Any, /, *, revivers: dict[str, collections.abc.Cal
         -5: -math.inf,
         -6: -0.0,
     }
+    lowest_valid_index = min(resolved.keys())
+
     if isinstance(parsed, int):
         if parsed == -2:
             raise ValueError('invalid input')
@@ -66,6 +68,10 @@ def parse_iter(parsed: typing.Any, /, *, revivers: dict[str, collections.abc.Cal
             target[index] = resolved[source]
             continue
 
+        if source < lowest_valid_index:
+            yield IndexError(f'invalid index: {source!r}')
+            continue
+
         value = parsed[source]
         if isinstance(value, list):
             if value and isinstance(value[0], str):