Bug 2567710 (CVE-2026-76077)

Summary: CVE-2026-76077 asn1scc: asn1scc: Arbitrary code execution via buffer overflow in XER tokenizer
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in asn1scc. The XML Encoding Rules (XER) tokenizer does not properly enforce length bounds when copying tag data and fails to check buffer limits during input processing. A remote attacker could exploit this vulnerability by providing a crafted XER message, leading to stack memory corruption or out-of-bounds reads. Successful exploitation could permit arbitrary code execution, disclosure of adjacent memory, or a Denial of Service (DoS) condition by crashing or hanging the decoder.
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Description OSIDB Bzimport 2026-11-05 22:19:52 UTC 
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.