diff --git a/library/x509_crt.c b/library/x509_crt.c
index 7389a9c..1ebe96a 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -751,6 +751,11 @@
         return ret;
     }
 
+    if (*p + len != end) {
+        return MBEDTLS_ERROR_ADD(MBEDTLS_ERR_X509_INVALID_EXTENSIONS,
+                                 MBEDTLS_ERR_ASN1_LENGTH_MISMATCH);
+    }
+
     if ((ret = mbedtls_asn1_get_tag(p, end, &len,
                                     MBEDTLS_ASN1_CONTEXT_SPECIFIC)) != 0) {
         /* KeyIdentifier is an OPTIONAL field */
diff --git a/tests/suites/test_suite_x509parse.data b/tests/suites/test_suite_x509parse.data
index 18c3c98..99834b2 100644
--- a/tests/suites/test_suite_x509parse.data
+++ b/tests/suites/test_suite_x509parse.data
@@ -3178,6 +3178,10 @@
 depends_on:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA:MBEDTLS_RSA_C
 x509_crt_parse_authoritykeyid:"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":20:"NL/PolarSSL/PolarSSL Test CA/":1:0
 
+X509 CRT parse Authority Key Id - Wrong Length
+depends_on:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA:MBEDTLS_RSA_C
+x509_crt_parse_authoritykeyid:"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":0:"":0:MBEDTLS_ERR_X509_INVALID_EXTENSIONS+MBEDTLS_ERR_ASN1_LENGTH_MISMATCH
+
 X509 CRT parse Authority Key Id - Wrong Sequence tag
 depends_on:MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA:MBEDTLS_RSA_C
 x509_crt_parse_authoritykeyid:"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":0:"":0:MBEDTLS_ERR_ASN1_UNEXPECTED_TAG