---
id: CVE-2026-75615
title: >-
  ASN1SCC: Out-of-bounds read via unvalidated character index in ASN.1 string
  decoders
summary: >-
  ASN1SCC is an open source ASN.1 compiler for embedded systems. Prior to
  4.7.0.1, the ACN runtime function Acn_Dec_String_CharIndex_private in
  asn1crt/asn1crt_encoding_acn.c and the generated uPER decoder
  InternalItem_string_with_alpha_de…
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-125
  - CWE-129
vendor: esa
product: asn1scc
affected:
  - asn1scc < 4.7.0.1
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T16:49:20.422Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-75615'
references:
  - url: 'https://github.com/esa/asn1scc/security/advisories/GHSA-234q-m7gr-pcf8'
    label: 'https://github.com/esa/asn1scc/security/advisories/GHSA-234q-m7gr-pcf8'
  - url: >-
      https://github.com/esa/asn1scc/commit/fe6ab763bc60d8a2def4104c15414809b45fffd9
    label: >-
      https://github.com/esa/asn1scc/commit/fe6ab763bc60d8a2def4104c15414809b45fffd9
  - url: 'https://github.com/esa/asn1scc/releases/tag/4.7.0.1'
    label: 'https://github.com/esa/asn1scc/releases/tag/4.7.0.1'
tags:
  - cve.org
ingestedAt: '2026-11-05T22:38:31.411Z'
---

## Overview

ASN1SCC is an open source ASN.1 compiler for embedded systems. Prior to 4.7.0.1, the ACN runtime function Acn_Dec_String_CharIndex_private in asn1crt/asn1crt_encoding_acn.c and the generated uPER decoder InternalItem_string_with_alpha_decode in StgC/uper_c.stg do not validate a decoded character index before reading allowedCharSet. For string alphabets whose size is not a power of two, a crafted message can select an unused encoded index, read a small bounded window of adjacent static program constants, and return the byte as a successfully decoded character. The full 128-character IA5String alphabet is not affected. This issue is fixed in version 4.7.0.1.

## Affected

- `asn1scc < 4.7.0.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.