{"id":"CVE-2026-32284","kind":"vulnerability","aliases":["CVE-2026-32284","GHSA-h9q6-hc68-35rp","GO-2026-4513"],"related":[],"title":"Denial of service in github.com/shamaton/msgpack","description":"The msgpack decoder fails to properly validate the input buffer length when processing truncated fixext data (format codes 0xd4-0xd8). This can lead to an out-of-bounds read and a runtime panic, allowing a denial of service attack.","summary":"The shamaton/msgpack Go library's decoder does not check buffer length for truncated fixext data, so a crafted msgpack input causes an out-of-bounds read and a runtime panic. An attacker who can send msgpack input to the service can crash the process, a denial of service.","severity":"high","cvss":7.5,"epss":0.00722,"exploited":false,"exploited_at":null,"products":[{"name":"github.com/shamaton/msgpack","fixed":[],"affected":"all versions","ecosystem":"go"},{"name":"github.com/shamaton/msgpack/v2","fixed":["2.4.1"],"affected":"< 2.4.1","ecosystem":"go"},{"name":"github.com/shamaton/msgpack/v3","fixed":["3.1.1"],"affected":"< 3.1.1","ecosystem":"go"}],"ecosystems":["go"],"tags":["go","msgpack","package","shamaton/msgpack"],"not_affected_if":["no-untrusted-msgpack-input","not-using-shamaton-msgpack"],"how_to_check":"Run govulncheck ./... in the Go module and look for GO-2026-4513; or check go.mod for github.com/shamaton/msgpack, msgpack/v2 below 2.4.1, or msgpack/v3 below 3.1.1.","fix":"Upgrade github.com/shamaton/msgpack/v2 to 2.4.1 or github.com/shamaton/msgpack/v3 to 3.1.1, then rebuild.\nThe unversioned github.com/shamaton/msgpack has no listed fix; the sources do not say which version to use.","status":"open","published_at":"2026-03-16T20:27:23+00:00","first_seen_at":"2026-10-23T19:13:08+00:00","triaged_at":"2026-10-23T21:45:43+00:00","updated_at":"2026-10-23T21:45:43+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-23T21:45:43Z","model":"claude-haiku-5-5","output":{"fix":"Upgrade github.com/shamaton/msgpack/v2 to 2.4.1 or github.com/shamaton/msgpack/v3 to 3.1.1, then rebuild.\nThe unversioned github.com/shamaton/msgpack has no listed fix; the sources do not say which version to use.","reach":"unknown","impact":"low","summary":"The shamaton/msgpack Go library's decoder does not check buffer length for truncated fixext data, so a crafted msgpack input causes an out-of-bounds read and a runtime panic. An attacker who can send msgpack input to the service can crash the process, a denial of service.","category":"package","who_cares":["go","msgpack","shamaton/msgpack"],"confidence":0.7,"needs_auth":"unknown","worst_case":"Attacker crashes the process via a crafted msgpack payload, causing denial of service.","analyst_note":"Confirm whether the unversioned github.com/shamaton/msgpack module has a fix and whether any service decodes untrusted msgpack; see https://pkg.go.dev/vuln/GO-2026-4513 and https://nvd.nist.gov/vuln/detail/CVE-2026-32284.","how_to_check":"Run govulncheck ./... in the Go module and look for GO-2026-4513; or check go.mod for github.com/shamaton/msgpack, msgpack/v2 below 2.4.1, or msgpack/v3 below 3.1.1.\nunknown","needs_analyst":true,"not_affected_if":["no-untrusted-msgpack-input","not-using-shamaton-msgpack"],"user_interaction":"no","needs_special_setup":"unknown","severity_if_unknown":"high"},"cost_usd":0.000589,"input_tokens":2948,"output_tokens":588,"severity_before":"high"},"analyst_status":null,"analyst_note":null,"search":"'-2026':9A,17A,20A '-32284':10A,21A '-4513':18A '/shamaton/msgpack':7A,24A '/shamaton/msgpack/v2':27A '/shamaton/msgpack/v3':30A '0xd4':103C '0xd4-0xd8':102C '0xd8':104C '35rp':15A 'allow':119C 'attack':67B,124C 'bound':60B,113C 'buffer':44B,93C 'caus':55B 'check':43B 'code':101C 'craft':52B 'crash':77B 'cve':8A,19A 'data':49B,99C 'decod':40B,86C 'denial':1A,81B,121C 'fail':87C 'fixext':48B,98C 'format':100C 'ghsa':12A 'ghsa-h9q6-hc68-35rp':11A 'github.com':6A,23A,26A,29A 'github.com/shamaton/msgpack':5A,22A 'github.com/shamaton/msgpack/v2':25A 'github.com/shamaton/msgpack/v3':28A 'go':16A,31B,37B 'h9q6':13A 'hc68':14A 'input':54B,72B,92C 'lead':107C 'length':45B,94C 'librari':38B 'msgpack':32B,53B,71B,85C 'out-of-bound':57B,110C 'packag':33B 'panic':65B,118C 'process':79B,96C 'proper':89C 'read':61B,114C 'runtim':64B,117C 'send':70B 'servic':3A,75B,83B,123C 'shamaton/msgpack':34B,36B 'truncat':47B,97C 'valid':90C","nicknames":[],"mitigations":[],"who_affected":null,"tier":null,"verified":{},"analyst_revisit_at":null,"first_public_at":"2026-03-16T20:27:23+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvss_by":"134c704f-9b21-4f2e-91b3-4a467353bcc0","poc_count":0,"sources":[{"source":"govuln","external_id":"GO-2026-4513","url":"https://pkg.go.dev/vuln/GO-2026-4513","severity":null,"published_at":"2026-03-16T20:27:23+00:00","modified_at":"2026-10-07T14:09:50+00:00","first_seen_at":"2026-10-23T19:13:08+00:00","fetched_at":"2026-10-23T19:13:08+00:00","note":null},{"source":"epss","external_id":"CVE-2026-32284","url":"https://api.first.org/data/v1/epss?cve=CVE-2026-32284","severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-10-23T19:13:43+00:00","fetched_at":"2026-10-23T19:13:43+00:00","note":null},{"source":"nvd","external_id":"CVE-2026-32284","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-32284","severity":null,"published_at":"2026-03-26T20:16:12+00:00","modified_at":"2026-10-07T18:17:20+00:00","first_seen_at":"2026-10-23T19:35:23+00:00","fetched_at":"2026-10-23T19:35:23+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}