From fc7710821efd02cc27a94f38fe6e70ffd7fc64b4 Mon Sep 17 00:00:00 2001
From: s0s <a+github@amadamackey.com>
Date: Tue, 24 Feb 2026 03:00:25 +0000
Subject: [PATCH] Common: fixes segmentation fault triggered by dereferencing
 value at negative index (#2198)

---
 src/common/impl/format.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/common/impl/format.c b/src/common/impl/format.c
index 469aceed4..5bea2d0c8 100644
--- a/src/common/impl/format.c
+++ b/src/common/impl/format.c
@@ -204,7 +204,7 @@ void ffParseFormatString(FFstrbuf* buffer, const FFstrbuf* formatstr, uint32_t n
             uint32_t index = getArgumentIndex(placeholderValue.chars, numArgs, arguments);
 
             // testing for an invalid index
-            if (index > numArgs)
+            if (index > numArgs || index < 1)
             {
                 appendInvalidPlaceholder(buffer, "{?", &placeholderValue, i, formatstr->length);
                 continue;
@@ -230,7 +230,7 @@ void ffParseFormatString(FFstrbuf* buffer, const FFstrbuf* formatstr, uint32_t n
             uint32_t index = getArgumentIndex(placeholderValue.chars, numArgs, arguments);
 
             // testing for an invalid index
-            if (index > numArgs)
+            if (index > numArgs || index < 1)
             {
                 appendInvalidPlaceholder(buffer, "{/", &placeholderValue, i, formatstr->length);
                 continue;