From fd8772ac3fd89fce5a0c26c59163c0ccd91aed7b Mon Sep 17 00:00:00 2001
From: Loganaden Velvindron <logan@cyberstorm.mu>
Date: Fri, 3 Jul 2026 03:57:58 +0400
Subject: [PATCH] quic: Fix buffer underflow

---
 src/quic.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/quic.c b/src/quic.c
index d178f66bce..dcdec84afe 100644
--- a/src/quic.c
+++ b/src/quic.c
@@ -852,6 +852,11 @@ static int wolfSSL_quic_send_internal(WOLFSSL* ssl)
             rl = (RecordLayerHeader*)output;
             ato16(rl->length, &rlen);
             output += RECORD_HEADER_SZ;
+            if (length < RECORD_HEADER_SZ) {
+                WOLFSSL_MSG("WOLFSSL_QUIC_SEND application failed");
+                ret = FWRITE_ERROR;
+                goto cleanup;
+            }
             length -= RECORD_HEADER_SZ;
             ssl->quic.output_rec_remain = rlen;
             ssl->quic.output_rec_level = ssl->quic.enc_level_write;