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CVE-2026-83557Proof of concept (PoC) published · CISA

jackson-databind omits java.lang.Comparable from DefaultBaseTypeLimitingValidator's unsafe base types

CVSS score

5.6

EPSS probability

%0.7

Risk score

0.0

Published

1 mo ago

Official patch verified

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Vulnerability description

DayBreach CVE AI Research

CVE-2026-83557 has vendor, distribution, patch and security-source records on file. We can compare them and prepare an explanation linked to the evidence.

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.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-83557 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1fasterxmljackson-databind View
2fasterxmljackson-databind View
3maventools.jackson.core:jackson-databind View
4maventools.jackson.core:jackson-databind View
5mavencom.fasterxml.jackson.core:jackson-databind View
6mavencom.fasterxml.jackson.core:jackson-databind View
7mavencom.fasterxml.jackson.core:jackson-databind View
Total affected vendors: 2|Products: 7

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
5.6CVSS V31MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:LNVD
5.6CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:LCVE CNA
5.6CVSS 3.x—Vector not publishedGitHub Advisory
0.0CVSS 4.0—Vector not publishedGitHub Advisory

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

cvelist

FasterXML/jackson-databind#6155

Open source
cvelist

Fix commit (2.x line, forward-merged to 2.21, 2.22 and the 3.x branches)

Open source
reference

FasterXML/jackson-databind#6155

Open source
reference

Fix commit (2.x line, forward-merged to 2.21, 2.22 and the 3.x branches)

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-83557 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-83557 weaknesses.

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

CVSS Vector Radar Chart

5.6 / 10
Attack VectorNetworkComplexityHighPrivilegesNoneUser Interact.NoneConfidentialityHighIntegrityNoneAvailabilityLow

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)High
Integrity (Bütünlük)None
Availability (Erişilebilirlik)Low

Yama doğrulandı

4 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

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