# CVE-2026-76077: ASN1SCC: Stack buffer overflow and out-of-bounds read in XER tokenizer NT()

Status: published. Published: 2026-11-05. Updated: 2026-11-05.

ASN1SCC is an open source ASN.1 compiler for embedded systems. Prior to 4.7.0.1, the XER tokenizer NT() in asn1crt/asn1crt_encoding_xer.c, which is reached by all XER decode paths, copies tag characters into a fixed char Value[100] field without a length bound and reads input and lookahead bytes without checking the buffer count. A crafted XER message with an overlong tag can overwrite the tokenizer's stack frame, while a truncated tag or unterminated processing-instruction or comment sequence can read beyond the input and may cause a CPU spin. The flaws can disclose adjacent memory, corrupt stack data, crash or hang the decoder, and potentially permit code execution. This issue is fixed in version 4.7.0.1.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- esa / asn1scc: < 4.7.0.1 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 8.1 (high); CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-120, CWE-125, CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/esa/asn1scc/security/advisories/GHSA-38q3-fg5h-wwf9 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/esa/asn1scc/commit/fe6ab763bc60d8a2def4104c15414809b45fffd9 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/esa/asn1scc/releases/tag/4.7.0.1 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-76077; retrieved 2026-11-05; source updated 2026-11-05

Revision: 8f06a5b0f8a33b7965b25469840296e6151b733af7a22d0747f0958d533d01c4

Canonical: https://y2.dev/cve/CVE-2026-76077

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