CVE-2026-102758 Memory corruption in NetX Duo

What is CVE-2026-102758?

CVE-2026-102758 is a high-severity memory corruption vulnerability in Eclipse Foundation NetX Duo, published on 29 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

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.

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.

Weakness: CWE-126

Which versions are affected by CVE-2026-102758?

How do I fix CVE-2026-102758?

No fix has been published for CVE-2026-102758 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2026-102758 being exploited?

There is no known exploitation of CVE-2026-102758 in the wild and no public exploit code.

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• GitHub advisory
• How this page is made

Also known as GHSA-f95g-xc4w-mrcr, GHSA-qfqh-8mhg-fcvw.