{"id":"CVE-2026-110879","kind":"vulnerability","aliases":["CVE-2026-110879"],"related":[],"title":"jackson-databind: generic type IDs bypass class validation, enabling remote code execution","description":"jackson-databind validates the outer class of a class-name type ID but accepts attacker-selected classes inside its generic arguments, even when those classes violate the declared type or would be rejected as direct type IDs. This bypasses the generic-argument validation added for CVE-2026-54512 (GHSA-j3rv-43j4-c7qm), of which this is an incomplete fix.\n\n\n\nDatabindContext._resolveAndValidateGeneric() checks the outer class against the declared base type and then passes each argument from the type ID to _validateTypeParameter(), which validates the argument against the outer base type rather than enforcing its corresponding declared generic binding. It also invokes validators with arguments that have not passed the subtype check those validators expect. Under the default DefaultBaseTypeLimitingValidator this accepts an unrelated class inside a generic subtype even when the same class is rejected as a direct type ID. Where an allowIfBaseType(...) rule approves the outer type, Jackson substitutes LaissezFaireSubTypeValidator, so the configured validator no longer restricts the embedded arguments. The element type of a plain array type ID such as [Lpkg.Gadget; is likewise left unvalidated once the array's base type is approved.\n\n\n\nAffected paths include annotation-based class-name polymorphism with a default Jackson 3.x JsonMapper, configured default typing in both Jackson 2.x and 3.x, and integrations that expose that default typing. The default-validator case requires no application-authored validator: with @JsonTypeInfo(use = Id.CLASS), a direct gadget type ID is rejected as \"Not a subtype\", while a type ID naming a generic wrapper around the same gadget is accepted and deserialized, including attacker-supplied bean properties. Where class-name default typing permits Map, a property declared as Map<String,String> accepts HashMap<FileSystemXmlApplicationContext,String>; map-key discovery then passes the attacker-controlled JSON property name to the selected class's one-string constructor. With Spring on the classpath and attacker-controlled XML the application can load, that constructor loads the XML and invokes ProcessBuilder.start() under the application account, giving arbitrary command execution.\n\n\n\nThis issue affects com.fasterxml.jackson.core:jackson-databind from 2.10.0 and tools.jackson.core:jackson-databind from 3.0.0. Releases before 2.10.0 are not affected, because PolymorphicTypeValidator was introduced in jackson-databind 2.10.0.","summary":"Jackson's class-name type validation checks the outer class of a generic type ID but not the classes passed as its generic arguments. An attacker who controls JSON input can make the server deserialize a gadget class, and with Spring on the classpath and attacker-controlled XML this reaches ProcessBuilder.start() and arbitrary command execution.","severity":"critical","cvss":9.8,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["jackson","java","package","self-hosted","spring"],"not_affected_if":["default-config","no-polymorphic-deserialization"],"how_to_check":"- Find the jackson-databind version in the build file or lockfile, for example with `mvn dependency:tree | grep jackson-databind` or `gradle dependencies | grep jackson-databind`\n- Check whether the application enables default typing or uses `@JsonTypeInfo(use = Id.CLASS)` on deserialized types\n- Check whether Spring is on the classpath","fix":"- Upgrade com.fasterxml.jackson.core:jackson-databind to a release that contains the fix for this issue (the fixed version is unknown from the sources)\n- Upgrade tools.jackson.core:jackson-databind to a fixed 3.x release (unknown from the sources)\n- Disable class-name default typing where it is not needed","status":"open","published_at":"2026-10-28T01:16:55+00:00","first_seen_at":"2026-10-28T01:30:10+00:00","triaged_at":"2026-10-28T01:31:41+00:00","updated_at":"2026-10-28T01:31:41+00:00","category":"package","confidence":0.7,"triage":{"at":"2026-10-28T01:31:41Z","model":"claude-haiku-5-5","output":{"fix":"- Upgrade com.fasterxml.jackson.core:jackson-databind to a release that contains the fix for this issue (the fixed version is unknown from the sources)\n- Upgrade tools.jackson.core:jackson-databind to a fixed 3.x release (unknown from the sources)\n- Disable class-name default typing where it is not needed","reach":"internet","title":"jackson-databind: generic type IDs bypass class validation, enabling remote code execution","impact":"high","summary":"Jackson's class-name type validation checks the outer class of a generic type ID but not the classes passed as its generic arguments. An attacker who controls JSON input can make the server deserialize a gadget class, and with Spring on the classpath and attacker-controlled XML this reaches ProcessBuilder.start() and arbitrary command execution.","category":"package","nicknames":[],"who_cares":["java","jackson","spring","self-hosted"],"confidence":0.7,"needs_auth":"no","worst_case":"Attacker runs arbitrary commands on the server as the application account.","analyst_note":"Fixed version numbers are not in the sources; check the NVD entry and the jackson-databind release notes for the patched 2.x and 3.x releases.","how_to_check":"- Find the jackson-databind version in the build file or lockfile, for example with `mvn dependency:tree | grep jackson-databind` or `gradle dependencies | grep jackson-databind`\n- Check whether the application enables default typing or uses `@JsonTypeInfo(use = Id.CLASS)` on deserialized types\n- Check whether Spring is on the classpath","needs_analyst":true,"not_affected_if":["default-config","no-polymorphic-deserialization"],"who_is_affected":"Applications that deserialize JSON with jackson-databind 2.10.0 or later, or tools.jackson.core 3.0.0 or later, where polymorphic class-name type IDs are accepted, through annotation-based polymorphism or configured default typing. Exposure is highest where Spring is on the classpath and the application loads attacker-controllable XML. Applications without polymorphic class-name deserialization are not exposed to this path.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"critical"},"cost_usd":0.000792,"input_tokens":4051,"output_tokens":774,"severity_before":"critical"},"analyst_status":null,"analyst_note":null,"search":"'-110879':16A,19A '-2026':15A,18A,134C '-54512':135C '2':295C '2.10.0':434C,444C,456C '3':286C,298C '3.0.0':441C '43j4':139C 'accept':99C,207C,346C,370C 'account':421C 'add':131C 'affect':272C,428C,447C 'allowifbasetyp':229C 'also':187C 'annot':276C 'annotation-bas':275C 'applic':315C,407C,420C 'application-author':314C 'approv':231C,271C 'arbitrari':81B,423C 'argument':51B,107C,129C,162C,172C,191C,247C 'around':341C 'array':254C,266C 'attack':53B,74B,101C,351C,382C,403C 'attacker-control':73B,381C,402C 'attacker-select':100C 'attacker-suppli':350C 'author':316C 'base':156C,176C,268C,277C 'bean':353C 'bind':185C 'bypass':7A,125C 'c7qm':140C 'case':311C 'check':34B,149C,198C 'class':8A,30B,37B,46B,65B,90C,94C,103C,111C,152C,210C,219C,279C,357C,390C 'class-nam':29B,93C,278C,356C 'classpath':71B,400C 'code':12A 'com.fasterxml.jackson.core':429C 'command':82B,424C 'configur':240C,289C 'constructor':395C,411C 'control':55B,75B,383C,404C 'correspond':182C 'cve':14A,17A,133C 'databind':3A,86C,432C,439C,455C 'databindcontext._resolveandvalidategeneric':148C 'declar':114C,155C,183C,365C 'default':204C,284C,290C,305C,309C,359C 'default-valid':308C 'defaultbasetypelimitingvalid':205C 'deseri':62B,348C 'direct':121C,224C,323C 'discoveri':377C 'element':249C 'embed':246C 'enabl':10A 'enforc':180C 'even':108C,215C 'execut':13A,83B,425C 'expect':201C 'expos':303C 'filesystemxmlapplicationcontext':372C 'fix':147C 'gadget':64B,324C,344C 'generic':4A,40B,50B,106C,128C,184C,213C,339C 'generic-argu':127C 'ghsa':137C 'ghsa-j3rv-43j4-c7qm':136C 'give':422C 'hashmap':371C 'host':25B 'id':6A,42B,97C,123C,166C,226C,256C,326C,336C 'id.class':321C 'includ':274C,349C 'incomplet':146C 'input':57B 'insid':104C,211C 'integr':301C 'introduc':451C 'invok':188C,416C 'issu':427C 'j3rv':138C 'jackson':2A,20B,27B,85C,235C,285C,294C,431C,438C,454C 'jackson-databind':1A,84C,430C,437C,453C 'java':21B 'json':56B,384C 'jsonmapp':288C 'jsontypeinfo':319C 'key':376C 'laissezfairesubtypevalid':237C 'left':262C 'likewis':261C 'load':409C,412C 'longer':243C 'lpkg.gadget':259C 'make':59B 'map':362C,367C,375C 'map-key':374C 'name':31B,95C,280C,337C,358C,386C 'one':393C 'one-str':392C 'outer':36B,89C,151C,175C,233C 'packag':22B 'pass':47B,160C,195C,379C 'path':273C 'permit':361C 'plain':253C 'polymorph':281C 'polymorphictypevalid':449C 'processbuilder.start':79B,417C 'properti':354C,364C,385C 'rather':178C 'reach':78B 'reject':119C,221C,328C 'releas':442C 'remot':11A 'requir':312C 'restrict':244C 'rule':230C 'select':102C,389C 'self':24B 'self-host':23B 'server':61B 'spring':26B,68B,397C 'string':368C,369C,373C,394C 'substitut':236C 'subtyp':197C,214C,332C 'suppli':352C 'tools.jackson.core':436C 'type':5A,32B,41B,96C,115C,122C,157C,165C,177C,225C,234C,250C,255C,269C,291C,306C,325C,335C,360C 'unrel':209C 'unvalid':263C 'use':320C 'valid':9A,33B,87C,130C,170C,189C,200C,241C,310C,317C 'validatetypeparamet':168C 'violat':112C 'would':117C 'wrapper':340C 'x':287C,296C,299C 'xml':76B,405C,414C","nicknames":[],"mitigations":[],"who_affected":"Applications that deserialize JSON with jackson-databind 2.10.0 or later, or tools.jackson.core 3.0.0 or later, where polymorphic class-name type IDs are accepted, through annotation-based polymorphism or configured default typing. Exposure is highest where Spring is on the classpath and the application loads attacker-controllable XML. Applications without polymorphic class-name deserialization are not exposed to this path.","tier":"B","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-28T01:16:55+00:00","kev":null,"cvss_vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cvss_by":"36c7be3b-2937-45df-85ea-ca7133ea542c","poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-110879","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-110879","severity":null,"published_at":"2026-10-28T01:16:55+00:00","modified_at":"2026-10-28T01:16:55+00:00","first_seen_at":"2026-10-28T01:30:10+00:00","fetched_at":"2026-10-28T01:30:10+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"}