CVE-2026-102758 (GCVE-0-2026-102758)
Vulnerability from cvelistv5 – Published: 2026-09-29 17:26 – Updated: 2026-09-30 20:42
VLAI
EPSS
VEX
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-30 20:42 UTC
CWE
- CWE-126 - Buffer Over-read
Assigner
References
1 reference
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| Eclipse Foundation | NetX Duo |
Affected:
0 , ≤ 6.5.1.202602
(custom)
Unaffected: 6.5.2.202603 |
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"value": "\u003cp\u003eThe `_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.\u003c/p\u003e\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003ecode:\u003c/p\u003e\u003cp\u003enx_secure/src/nx_secure_x509_asn1_tlv_block_parse.c\u003c/p\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003eUINT _nx_secure_x509_asn1_tlv_block_parse(const UCHAR *buffer, ULONG *buffer_length, USHORT *tlv_type,\u003c/p\u003e\u003ccode\u003e USHORT *tlv_tag_class, ULONG *tlv_length,\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e const UCHAR **tlv_data, ULONG *header_length)\u003c/code\u003e\u003cbr\u003e\u003cp\u003e{\u003c/p\u003e\u003cp\u003eUINT current_index;\u003c/p\u003e\u003cp\u003eUSHORT current_tag;\u003c/p\u003e\u003cp\u003eULONG length;\u003c/p\u003e\u003cp\u003eULONG length_bytes;\u003c/p\u003e\u003ccode\u003e current_index = 0;\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e current_tag = buffer[current_index]; /* \u0026lt;-- read before the bounds check */\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e if (*buffer_length \u0026lt; 1)\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e {\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e return(NX_SECURE_X509_ASN1_LENGTH_TOO_LONG);\u003c/code\u003e\u003cbr\u003e\u003ccode\u003e }\u003c/code\u003e\u003cbr\u003e\u003cp\u003e```\u003c/p\u003e\u003cp\u003eThe remainder of the function is correctly ordered. The multi-byte length path is guarded by `length_bytes \u0026gt; 4 || length_bytes \u0026gt; *buffer_length` before its read loop, the decoded value is checked against `length \u0026gt; *buffer_length`, and the second single-byte length read follows its own `*buffer_length \u0026lt; 1` guard. The tag read is the only load placed ahead of its check.\u003c/p\u003e"
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Published Proof of Concept: A public proof of concept is available for this vulnerability.
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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