{"id":"CVE-2026-116486","kind":"vulnerability","aliases":["CVE-2026-116486"],"related":[],"title":"Objenesis: class cache collision lets one loader substitute objects into another","description":"Objenesis before 3.6 contains a type confusion vulnerability that allows code in one class loader to substitute objects into another by exploiting instantiator caching keyed on class name. When a shared ObjenesisStd instance caches instantiators by clazz.getName() in ObjenesisBase.getInstantiatorOf(), same-named classes collide, causing newInstance() to return wrong-class objects and ClassCastException failures.","summary":"Objenesis before 3.6 caches instantiators by class name, so two same-named classes from different class loaders can collide in a shared ObjenesisStd instance. The result is newInstance() returning objects of the wrong class, causing ClassCastException failures and possible substitution of objects across loaders.","severity":"medium","cvss":4.5,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["java","jvm","mockito","objenesis","package"],"not_affected_if":["no-shared-instance","single-class-loader"],"how_to_check":"- Look for `org.objenesis:objenesis` in your build files (`mvn dependency:tree | grep objenesis` or `gradle dependencies | grep objenesis`) and note the resolved version.\n- Check whether code shares a single `ObjenesisStd` instance across multiple class loaders, such as in an app server, plugin system, or test framework.","fix":"- Upgrade `org.objenesis:objenesis` to `3.6` or later.\n- If upgrading is not possible, avoid sharing one `ObjenesisStd` instance across class loaders.","status":"open","published_at":"2026-10-26T14:16:37+00:00","first_seen_at":"2026-10-26T14:30:37+00:00","triaged_at":"2026-10-26T14:32:50+00:00","updated_at":"2026-10-26T14:32:50+00:00","category":"package","confidence":0.6,"triage":{"at":"2026-10-26T14:32:50Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade `org.objenesis:objenesis` to `3.6` or later.\n- If upgrading is not possible, avoid sharing one `ObjenesisStd` instance across class loaders.","reach":"local","title":"Objenesis: class cache collision lets one loader substitute objects into another","impact":"medium","summary":"Objenesis before 3.6 caches instantiators by class name, so two same-named classes from different class loaders can collide in a shared ObjenesisStd instance. The result is newInstance() returning objects of the wrong class, causing ClassCastException failures and possible substitution of objects across loaders.","category":"package","nicknames":[],"who_cares":["java","objenesis","mockito","jvm"],"confidence":0.6,"needs_auth":"unknown","worst_case":"Wrong-class objects returned, causing ClassCastException failures and cross-loader object substitution","analyst_note":"","how_to_check":"- Look for `org.objenesis:objenesis` in your build files (`mvn dependency:tree | grep objenesis` or `gradle dependencies | grep objenesis`) and note the resolved version.\n- Check whether code shares a single `ObjenesisStd` instance across multiple class loaders, such as in an app server, plugin system, or test framework.","needs_analyst":false,"not_affected_if":["single-class-loader","no-shared-instance"],"who_is_affected":"Projects that depend on Objenesis below 3.6 and use it in an environment where several class loaders load same-named classes through one shared ObjenesisStd instance, such as plugin containers or application servers. Single-loader applications and those that create a fresh Objenesis instance per loader are unlikely to be affected; the sources do not quantify this further.","user_interaction":"unknown","needs_special_setup":"yes","severity_if_unknown":"medium"},"cost_usd":0.000651,"input_tokens":3358,"output_tokens":631,"severity_before":"medium"},"analyst_status":null,"analyst_note":null,"search":"'-116486':14A,17A '-2026':13A,16A '3.6':25B,70C 'across':66B 'allow':77C 'anoth':11A,87C 'cach':3A,26B,91C,101C 'caus':58B,112C 'class':2A,29B,36B,39B,57B,81C,94C,110C,118C 'classcastexcept':59B,121C 'clazz.getname':104C 'code':78C 'collid':42B,111C 'collis':4A 'confus':74C 'contain':71C 'cve':12A,15A 'differ':38B 'exploit':89C 'failur':60B,122C 'instanc':47B,100C 'instanti':27B,90C,102C 'java':18B 'jvm':19B 'key':92C 'let':5A 'loader':7A,40B,67B,82C 'mockito':20B 'name':30B,35B,95C,109C 'newinst':51B,113C 'object':9A,53B,65B,85C,119C 'objenesi':1A,21B,23B,68C 'objenesisbase.getinstantiatorof':106C 'objenesisstd':46B,99C 'one':6A,80C 'packag':22B 'possibl':62B 'result':49B 'return':52B,115C 'same-nam':33B,107C 'share':45B,98C 'substitut':8A,63B,84C 'two':32B 'type':73C 'vulner':75C 'wrong':56B,117C 'wrong-class':116C","nicknames":[],"mitigations":[],"who_affected":"Projects that depend on Objenesis below 3.6 and use it in an environment where several class loaders load same-named classes through one shared ObjenesisStd instance, such as plugin containers or application servers. Single-loader applications and those that create a fresh Objenesis instance per loader are unlikely to be affected; the sources do not quantify this further.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-26T14:16:37+00:00","kev":null,"cvss_vector":"CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","cvss_by":"disclosure@vulncheck.com","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-116486","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-116486","severity":null,"published_at":"2026-10-26T14:16:37+00:00","modified_at":"2026-10-26T14:16:37+00:00","first_seen_at":"2026-10-26T14:30:37+00:00","fetched_at":"2026-10-26T14:30:37+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"}