# CVE-2026-83557: jackson-databind: DefaultBaseTypeLimitingValidator is the PolymorphicTypeValidator applied automatically whenever @JsonTypeInfo is used... CVE-2026-83557 is fixed in 5 products on 1 platform, first by DEBIAN-CVE-2026-83557, released September 1, 2026. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2026-83557 - Priority: Routine - CVSS: 5.6 (medium) - EPSS: 0.0072 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 1, 2026 ## Description DefaultBaseTypeLimitingValidator is the PolymorphicTypeValidator applied automatically whenever @JsonTypeInfo is used without an explicitly configured custom validator. It denies polymorphic resolution only for a fixed set of "unsafe base types", and its isSafeSubType method returns true unconditionally for every base type outside that set. java.lang.Comparable was absent from the list despite being implemented by a very large fraction of JDK and application classes, comparable in breadth to java.io.Serializable, which is on the list for that reason. An application declaring an @JsonTypeInfo-annotated property or class with Comparable as its base type, and no custom PolymorphicTypeValidator, will accept a type identifier for essentially any class implementing Comparable. This yields an attacker-controlled object instantiation primitive; a demonstrated case constructs a java.io.File for an arbitrary attacker-chosen path, which becomes path-traversal-adjacent if the application subsequently calls path-sensitive methods on the value. No class implementing Comparable has been identified that yields code execution through deserialization alone. Global Default Typing via activateDefaultTyping is not affected, because that method structurally requires an explicit PolymorphicTypeValidator argument. This affects com.fasterxml.jackson.core:jackson-databind from 2.11.0 before 2.18.10, from 2.19.0 before 2.21.6, and from 2.22.0 before 2.22.2, and tools.jackson.core:jackson-databind from 3.0.0 before 3.1.6 and from 3.2.0 before 3.2.2. Users should upgrade to 2.18.10, 2.21.6, 2.22.2, 3.1.6, or 3.2.2. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | jackson-annotations opensuse-leap 16.0 | 2.18.11-160000.1.1 | [OPENSUSE-SU-2026:22034-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22034-1.md) | Oct 6, 2026 | | Linux | jackson-annotations sles 15.6 | 2.18.11-150200.3.28.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-annotations sles 15.7 | 2.18.11-150200.3.28.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-annotations sles 16.0 | 2.18.11-160000.1.1 | [SUSE-SU-2026:24149-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24149-1.md) | Oct 6, 2026 | | Linux | jackson-core opensuse-leap 16.0 | 2.18.11-160000.1.1 | [OPENSUSE-SU-2026:22034-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22034-1.md) | Oct 6, 2026 | | Linux | jackson-core sles 15.6 | 2.18.11-150200.3.30.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-core sles 15.7 | 2.18.11-150200.3.30.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-core sles 16.0 | 2.18.11-160000.1.1 | [SUSE-SU-2026:24149-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24149-1.md) | Oct 6, 2026 | | Linux | jackson-databind Debian 14 | 2.18.11-1 | [DEBIAN-CVE-2026-83557](https://patchblox.com/security/data/fix/linux/debian-cve-2026-83557.md) | Sep 1, 2026 | | Linux | jackson-databind amzn 2023 | 2.21.7-1.amzn2023.0.1 | [ALAS2023-2026-3305](https://patchblox.com/security/data/fix/linux/alas2023-2026-3305.md) | Nov 7, 2026 | | Linux | jackson-databind opensuse-leap 16.0 | 2.18.11-160000.1.1 | [OPENSUSE-SU-2026:22034-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22034-1.md) | Oct 6, 2026 | | Linux | jackson-databind sles 15.6 | 2.18.11-150200.3.36.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-databind sles 15.7 | 2.18.11-150200.3.36.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-databind sles 16.0 | 2.18.11-160000.1.1 | [SUSE-SU-2026:24149-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-24149-1.md) | Oct 6, 2026 | | Linux | jackson-dataformat-xml sles 15.6 | 2.18.11-150200.5.8.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-dataformat-xml sles 15.7 | 2.18.11-150200.5.8.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-dataformats-binary sles 15.6 | 2.18.11-150200.3.29.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | | Linux | jackson-dataformats-binary sles 15.7 | 2.18.11-150200.3.29.1 | [SUSE-SU-2026:4394-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4394-1.md) | Sep 29, 2026 | --- Data as of 2026-11-09T19:38:12Z UTC. 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