GHSA-QFQH-8MHG-FCVW
Vulnerability from github – Published: 2026-09-29 18:32 – Updated: 2026-09-30 21:31The _nx_secure_x509_asn1_tlv_block_parse() function parses ASN.1 TLV (tag-length-value) blocks out of DER-encoded data. It is the primitive underneath all X.509 certificate parsing in NetX Secure, and therefore runs on certificates supplied by a remote peer during the TLS handshake.
The function reads the one-byte ASN.1 tag from the caller's buffer before checking that the buffer holds at least one byte. When a caller passes a remaining length of zero, the guard correctly returns NX_SECURE_X509_ASN1_LENGTH_TOO_LONG, but the read has already happened one byte past the end of the buffer.
code:
nx_secure/src/nx_secure_x509_asn1_tlv_block_parse.c
UINT _nx_secure_x509_asn1_tlv_block_parse(const UCHAR *buffer, ULONG *buffer_length, USHORT *tlv_type,
USHORT *tlv_tag_class, ULONG *tlv_length,
const UCHAR **tlv_data, ULONG *header_length)
{
UINT current_index;
USHORT current_tag;
ULONG length;
ULONG length_bytes;
current_index = 0;
current_tag = buffer[current_index]; /* <-- read before the bounds check */
if (*buffer_length < 1)
{
return(NX_SECURE_X509_ASN1_LENGTH_TOO_LONG);
}
The remainder of the function is correctly ordered. The multi-byte length path is guarded by length_bytes > 4 || length_bytes > *buffer_length before its read loop, the decoded value is checked against length > *buffer_length, and the second single-byte length read follows its own *buffer_length < 1 guard. The tag read is the only load placed ahead of its check.
{
"affected": [],
"aliases": [
"CVE-2026-102758"
],
"database_specific": {
"cwe_ids": [
"CWE-126"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-29T18:17:13Z",
"severity": "HIGH"
},
"details": "The `_nx_secure_x509_asn1_tlv_block_parse()` function parses ASN.1 TLV (tag-length-value) blocks out of DER-encoded data. It is the primitive underneath all X.509 certificate parsing in NetX Secure, and therefore runs on certificates supplied by a remote peer during the TLS handshake.\n\n\n\nThe function reads the one-byte ASN.1 tag from the caller\u0027s buffer *before* checking that the buffer holds at least one byte. When a caller passes a remaining length of zero, the guard correctly returns `NX_SECURE_X509_ASN1_LENGTH_TOO_LONG`, but the read has already happened one byte past the end of the buffer.\n\n\n\ncode:\n\n\n\nnx_secure/src/nx_secure_x509_asn1_tlv_block_parse.c\n\n\n\n```\n\n\n\nUINT _nx_secure_x509_asn1_tlv_block_parse(const UCHAR *buffer, ULONG *buffer_length, USHORT *tlv_type,\n\n USHORT *tlv_tag_class, ULONG *tlv_length,\n const UCHAR **tlv_data, ULONG *header_length)\n\n\n{\n\n\n\nUINT current_index;\n\n\n\nUSHORT current_tag;\n\n\n\nULONG length;\n\n\n\nULONG length_bytes;\n\n current_index = 0;\n current_tag = buffer[current_index]; /* \u003c-- read before the bounds check */\n if (*buffer_length \u003c 1)\n {\n return(NX_SECURE_X509_ASN1_LENGTH_TOO_LONG);\n }\n\n\n```\n\n\n\nThe remainder of the function is correctly ordered. The multi-byte length path is guarded by `length_bytes \u003e 4 || length_bytes \u003e *buffer_length` before its read loop, the decoded value is checked against `length \u003e *buffer_length`, and the second single-byte length read follows its own `*buffer_length \u003c 1` guard. The tag read is the only load placed ahead of its check.",
"id": "GHSA-qfqh-8mhg-fcvw",
"modified": "2026-09-30T21:31:59Z",
"published": "2026-09-29T18:32:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/eclipse-threadx/netxduo/security/advisories/GHSA-f95g-xc4w-mrcr"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102758"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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