From 4da84019ccec87fea161797af2901244fa5f170e Mon Sep 17 00:00:00 2001
From: Tobias Brunner <tobias@strongswan.org>
Date: Wed, 25 Mar 2026 10:28:45 +0100
Subject: [PATCH] pkcs5: Avoid NULL pointer dereference when verifying padding

Can be triggered via empty PKCS#7 encrypted content in IKEv1 CERT payload.

Fixes: 4076e3ee9121 ("Extract PKCS#5 handling from pkcs8 plugin to separate helper class")
Fixes: CVE-2026-35329
---
 src/libstrongswan/crypto/pkcs5.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libstrongswan/crypto/pkcs5.c b/src/libstrongswan/crypto/pkcs5.c
index e48a9ad9d..4851d3f96 100644
--- a/src/libstrongswan/crypto/pkcs5.c
+++ b/src/libstrongswan/crypto/pkcs5.c
@@ -113,6 +113,11 @@ static bool verify_padding(crypter_t *crypter, chunk_t *blob)
 {
 	uint8_t padding, count;
 
+	if (!blob->len)
+	{
+		return FALSE;
+	}
+
 	padding = count = blob->ptr[blob->len - 1];
 
 	if (padding > crypter->get_block_size(crypter))