1 files changed, 10 insertions, 2 deletions

diff --git a/libbb/process_escape_sequence.c b/libbb/process_escape_sequence.c
index 59d0d3ea8..11adbfcea 100644
--- a/libbb/process_escape_sequence.c
+++ b/libbb/process_escape_sequence.c
@@ -41,8 +41,16 @@ char FAST_FUNC bb_process_escape_sequence(const char **ptr)
                 unsigned d = (unsigned char)(*q) - '0';
 #else
                 unsigned d = (unsigned char)_tolower(*q) - '0';
-                if (d >= 10)
-                        d += ('0' - 'a' + 10);
+                if (d >= 10) {
+                        //d += ('0' - 'a' + 10);
+                        /* The above would maps '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:
+                         */
+                        d += ('0' - 'a');
+                        if ((int)d >= 0)
+                                d += 10;
+                }
 #endif
                 if (d >= base) {
                         if (WANT_HEX_ESCAPES && base == 16) {