{"id":"CVE-2026-103636","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-103636","generatedAt":"2026-10-28T01:03:29.528Z","title":"Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (repo: datasketches-cpp). var_opt_union::deserialize() read the 32-byte preamble of a non-empty union after checking that only 8 bytes were available, so a truncated…","description":"Out-of-bounds read in the VarOpt union deserialization of Apache DataSketches C++ (repo: datasketches-cpp).\n\nvar_opt_union::deserialize() read the 32-byte preamble of a non-empty union after checking that only 8 bytes were available, so a truncated serialized union could cause a read of up to 24 bytes past the end of the input. For such inputs, the size remaining for the embedded sketch was also computed by an unsigned subtraction that could wrap around, so the embedded sketch's own size checks no longer limited reads to the input. The bytes read can become part of the deserialized union's state. This can cause a crash (denial of service) and could expose adjacent memory contents.\n\nThis issue affects Apache DataSketches C++: from 2.0.0-incubating before 5.3.0. Only applications that deserialize VarOpt unions from untrusted sources are affected.\n\nUsers are recommended to upgrade to version 5.3.0, which fixes this issue.","published":"2026-10-10T11:17:36.000Z","lastModified":"2026-10-16T16:16:54.000Z","status":"Undergoing Analysis","sourceIdentifier":"security@apache.org","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-125","CWE-191"],"affected":[],"epss":{"score":0.0038,"percentile":0.31704,"date":"2026-10-26","history":[{"date":"2026-10-11","score":0.00238,"percentile":0.13663}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.38%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"scored","label":"Newly scored","at":"2026-10-16T17:00:51.000Z","detail":{"from":null,"score":"7.5","severity":"HIGH","fromSeverity":null},"summary":"Now scored CVSS 7.5 HIGH."},{"kind":"new","label":"New CVE","at":"2026-10-10T11:17:36.000Z","detail":{"score":null,"severity":null,"publishedAt":"2026-10-10T11:17:36.077Z"},"summary":"New CVE, high severity (CVSS 7.5)."}],"references":[{"url":"https://github.com/apache/datasketches-cpp/releases/tag/5.3.0","source":"security@apache.org"},{"url":"https://lists.apache.org/thread/znn94s463w7wy125khcywxsp82y2qkq5","source":"security@apache.org"},{"url":"http://www.openwall.com/lists/oss-security/2026/10/10/6","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-103636","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}