From: Thomas Pornin <thomas.pornin@nccgroup.com>
Date: Mon, 6 Apr 2026 13:40:05 +0000 (-0400)
Subject: Fixed bug in handling incoming records with invalid length (impacted CBC encryption... 
X-Git-Url: https://www.bearssl.org/gitweb//home/git/?a=commitdiff_plain;h=7bea48e5e850ab4cafbe68d3765cdaba13a86d6f;p=BearSSL

Fixed bug in handling incoming records with invalid length (impacted CBC encryption with 3DES or with the aes_small or aes_big AES implementations; only 3DES was selectable by default).

Bug was reported by Thai Duong at Calif.io (with some AI stuff from Anthropic Research).
---

diff --git a/src/ssl/ssl_rec_cbc.c b/src/ssl/ssl_rec_cbc.c
index c38cbfd..9e89bb6 100644
--- a/src/ssl/ssl_rec_cbc.c
+++ b/src/ssl/ssl_rec_cbc.c
@@ -70,7 +70,7 @@ cbc_check_length(const br_sslrec_in_cbc_context *cc, size_t rlen)
 		min_len += blen;
 		max_len += blen;
 	}
-	return min_len <= rlen && rlen <= max_len;
+	return min_len <= rlen && rlen <= max_len && (rlen & (blen - 1)) == 0;
 }
 
 /*