{"id":"CVE-2026-76077","kind":"vulnerability","aliases":["CVE-2026-76077"],"related":[],"title":"ASN1SCC: XER decoder stack overflow lets crafted messages run code","description":"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.","summary":"ASN1SCC is an open source ASN.1 compiler for embedded systems. A crafted XER message with an overlong tag can overwrite the decoder's stack and read past the input, which can leak memory, crash or hang the decoder, and potentially run code.","severity":"high","cvss":8.1,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["asn1scc","c","embedded","package","xer"],"not_affected_if":["no-xer-decoding","trusted-input-only"],"how_to_check":"- Check the ASN1SCC version in your build: `unknown` if the project does not record it, otherwise compare against `4.7.0.1`.\n- Look for XER decoding in your code, since all XER decode paths reach the affected tokenizer.","fix":"- ASN1SCC: move to `4.7.0.1` or later.","status":"open","published_at":"2026-11-05T17:18:20+00:00","first_seen_at":"2026-11-05T17:40:05+00:00","triaged_at":"2026-11-05T17:42:15+00:00","updated_at":"2026-11-05T17:42:15+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-11-05T17:42:15Z","model":"claude-haiku-5-5","output":{"fix":"- ASN1SCC: move to `4.7.0.1` or later.","reach":"unknown","title":"ASN1SCC: XER decoder stack overflow lets crafted messages run code","impact":"high","summary":"ASN1SCC is an open source ASN.1 compiler for embedded systems. A crafted XER message with an overlong tag can overwrite the decoder's stack and read past the input, which can leak memory, crash or hang the decoder, and potentially run code.","audience":"developers","category":"package","nicknames":[],"who_cares":["asn1scc","embedded","xer","c"],"confidence":0.6,"fix_status":"available","needs_auth":"unknown","worst_case":"code runs in the decoder, memory leaks, decoder crashes or hangs","analyst_note":"Confirm the exact affected versions and whether a remote input path exists in typical deployments; check the linked release notes for the 4.7.0.1 fix details.","how_to_check":"- Check the ASN1SCC version in your build: `unknown` if the project does not record it, otherwise compare against `4.7.0.1`.\n- Look for XER decoding in your code, since all XER decode paths reach the affected tokenizer.","plain_action":"","needs_analyst":true,"not_affected_if":["no-xer-decoding","trusted-input-only"],"who_is_affected":"Teams that compile ASN.1 schemas with ASN1SCC and decode XER-encoded messages, especially embedded systems that accept XER input from outside. Systems that only use other encodings, or never decode untrusted XER, are less exposed.","user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000732,"input_tokens":4419,"output_tokens":581,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-2026':12A,15A '-76077':13A,16A '100':99C '4.7.0.1':76C,179C 'adjac':158C 'asn.1':27B,69C 'asn1crt/asn1crt_encoding_xer.c':82C 'asn1scc':1A,17B,22B,64C 'beyond':145C 'bound':104C 'buffer':114C 'byte':110C 'c':18B 'caus':150C 'char':97C 'charact':93C 'check':112C 'code':10A,63B,171C 'comment':141C 'compil':28B,70C 'copi':91C 'corrupt':160C 'count':115C 'cpu':152C 'craft':7A,33B,117C 'crash':55B,163C 'cve':11A,14A 'data':162C 'decod':3A,43B,59B,89C,167C 'disclos':157C 'embed':19B,30B,72C 'execut':172C 'field':100C 'fix':96C,176C 'flaw':155C 'frame':130C 'hang':57B,165C 'input':50B,107C,147C 'instruct':139C 'issu':174C 'leak':53B 'length':103C 'let':6A 'lookahead':109C 'may':149C 'memori':54B,159C 'messag':8A,35B,119C 'nt':80C 'open':25B,67C 'overflow':5A 'overlong':38B,122C 'overwrit':41B,125C 'packag':20B 'past':48B 'path':90C 'permit':170C 'potenti':61B,169C 'prior':74C 'process':138C 'processing-instruct':137C 'reach':85C 'read':47B,106C,144C 'run':9A,62B 'sequenc':142C 'sourc':26B,68C 'spin':153C 'stack':4A,45B,129C,161C 'system':31B,73C 'tag':39B,92C,123C,134C 'token':79C,127C 'truncat':133C 'untermin':136C 'valu':98C 'version':178C 'without':101C,111C 'xer':2A,21B,34B,78C,88C,118C","nicknames":[],"mitigations":[],"who_affected":"Teams that compile ASN.1 schemas with ASN1SCC and decode XER-encoded messages, especially embedded systems that accept XER input from outside. Systems that only use other encodings, or never decode untrusted XER, are less exposed.","tier":"B","verified":{},"analyst_revisit_at":null,"fix_status":"available","audience":"developers","plain_action":null,"pkeys":[],"ptokens":[],"labels":["asn1scc","c","embedded","high","package","xer"],"campaign_type":null,"first_public_at":"2026-07-11T11:35:02+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"security-advisories@github.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-76077","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-76077","severity":null,"published_at":"2026-11-05T17:18:20+00:00","modified_at":"2026-11-05T17:18:20+00:00","first_seen_at":"2026-11-05T17:40:05+00:00","fetched_at":"2026-11-05T17:40:05+00:00","note":null}],"documents":[{"id":78128,"url":"https://github.com/esa/asn1scc/commit/fe6ab763bc60d8a2def4104c15414809b45fffd9","title":"Patch: github.com","kind":"other","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Patch: github.com"},{"id":78129,"url":"https://github.com/esa/asn1scc/releases/tag/4.7.0.1","title":"Release notes: github.com","kind":"release","source":"nvd","publisher":"vendor","text":null,"published_at":null,"relation":"fix","confidence":null,"note":"Release notes: github.com"},{"id":78136,"url":"https://github.com/esa/asn1scc/security/advisories/GHSA-38q3-fg5h-wwf9","title":"Vendor advisory: github.com","kind":"vendor","source":"nvd","publisher":"vendor","text":null,"published_at":"2026-07-11T11:35:02+00:00","relation":"advisory","confidence":null,"note":"Vendor advisory: github.com"}],"exploit_sources":[],"notice":"Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai"}