1 files changed, 11 insertions, 5 deletions

diff --git a/libbb/process_escape_sequence.c b/libbb/process_escape_sequence.c
index 59d0d3ea8..13022b83e 100644
--- a/libbb/process_escape_sequence.c
+++ b/libbb/process_escape_sequence.c
@@ -37,12 +37,18 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
          * We treat \2 as a valid octal escape sequence. */
         do {
                 unsigned r;
-#if !WANT_HEX_ESCAPES
                 unsigned d = (unsigned char)(*q) - '0';
-#else
-                unsigned d = (unsigned char)_tolower(*q) - '0';
-                if (d >= 10)
-                        d += ('0' - 'a' + 10);
+#if WANT_HEX_ESCAPES
+                if (d >= 10) {
+                        d = (unsigned char)_tolower(*q) - 'a';
+                        //d += 10;
+                        /* The above would map 'A'-'F' and 'a'-'f' to 10-15,
+                         * however, some chars like '@' would map to 9 < base.
+                         * Do not allow that, map invalid chars to N > base:
+                         */
+                        if ((int)d >= 0)
+                                d += 10;
+                }
 #endif
                 if (d >= base) {
                         if (WANT_HEX_ESCAPES && base == 16) {