CVE-2026-91776

jackson-databind · Vulnerability

CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-91776

Published

TypeDeserializerBase._findDeserializer() in FasterXML jackson-databind caches the resolved deserializer under the raw, attacker-supplied type ID. When name-based polymorphism is configured with a fallback, for example @JsonTypeInfo(use = Id.NAME, defaultImpl = ...), every distinct unrecognized type ID resolves to the same fallback deserializer but is retained as its own key in the _deserializers map. That map has no configurable bound and lives for the lifetime of the type deserializer, so an attacker who can repeatedly supply fresh unknown type IDs causes monotonic memory retention across requests. The reporter observed 10,000 retained entries from 10,000 distinct unknown IDs, against a single entry for a control that repeated one unknown ID the same number of times, isolating attacker-controlled key cardinality from request volume. Exploitation requires an application that enables name-based polymorphism with a defaultImpl or equivalent fallback, accepts attacker-influenced type IDs, and reuses a long-lived ObjectMapper across requests. The fix stops caching fallback resolutions for unrecognized IDs and bounds both the number of cached entries and the length of a cacheable type ID.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-91776

Published

com.fasterxml.jackson.core:jackson-databind

https://repo1.maven.org/maven2

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "FasterXML",
                    "product": "jackson-databind",
                    "collectionURL": "https://repo1.maven.org/maven2",
                    "packageName": "com.fasterxml.jackson.core:jackson-databind",
                    "repo": "https://github.com/FasterXML/jackson-databind",
                    "programRoutines": [
                        {
                            "name": "com.fasterxml.jackson.databind.jsontype.impl.TypeDeserializerBase._findDeserializer"
                        }
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "2.0.0",
                            "lessThanOrEqual": "2.18.10",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.19.0",
                            "lessThanOrEqual": "2.21.6",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "2.22.0",
                            "lessThanOrEqual": "2.22.2",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

tools.jackson.core:jackson-databind

https://repo1.maven.org/maven2

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "FasterXML",
                    "product": "jackson-databind",
                    "collectionURL": "https://repo1.maven.org/maven2",
                    "packageName": "tools.jackson.core:jackson-databind",
                    "repo": "https://github.com/FasterXML/jackson-databind",
                    "programRoutines": [
                        {
                            "name": "tools.jackson.databind.jsontype.impl.TypeDeserializerBase._findDeserializer"
                        }
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "3.0.0",
                            "lessThanOrEqual": "3.1.6",
                            "versionType": "maven"
                        },
                        {
                            "status": "affected",
                            "version": "3.2.0",
                            "lessThanOrEqual": "3.2.2",
                            "versionType": "maven"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

Original source record · Cite this exact observation · Complete original publisher JSON