Skip to content
Fencer Vulns
medium 6.9

CVE-2026-18401 json

jackson-core: Number length constraint bypass in non-blocking (async) JSON parser leads to potential denial of service

published 2026-02-28 8 mo ago modified 2026-10-23 16 d ago also EUVD-2026-52699 , GHSA-72hv-8253-57qq

cvss
6.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

The non-blocking (asynchronous) JSON parser in jackson-core does not enforce the maxNumberLength constraint defined in StreamReadConstraints (default: 1000 characters). An attacker able to submit JSON to an application that uses the async parser API can supply a number token of arbitrary length, leading to excessive memory allocation and potential CPU exhaustion, resulting in a denial of service.

The synchronous parser enforces this limit correctly, so the constraint is applied inconsistently depending on which parsing API the application uses.

Root cause: the async parsing path in NonBlockingUtf8JsonParserBase and related classes never invokes the number length validation methods. Number parsing methods such as _finishNumberIntegralPart() accumulate digits into the TextBuffer without any length check, then call _valueComplete() to finalize the token. _valueComplete() does not call resetInt() or resetFloat(), which are the methods in ParserBase where validateIntegerLength() and validateFPLength() are performed. Because that validation step is skipped, maxNumberLength is never enforced on the async code path.

Impact: an attacker sending a JSON document containing an arbitrarily long number to an application using the async parser (for example a Spring WebFlux or other reactive application) can cause unbounded allocation in the TextBuffer and an OutOfMemoryError. If the application subsequently calls getBigIntegerValue() or getDecimalValue(), the JVM may additionally be tied up in O(n^2) BigInteger parsing, causing CPU-based denial of service.

No privileges or user interaction beyond the ability to submit data for parsing are required.

This issue affects com.fasterxml.jackson.core:jackson-core from version 2.15.0 through 2.18.5 and from 2.19.0 through 2.21.0, and tools.jackson.core:jackson-core from 3.0.0 through 3.0.x.

Versions prior to 2.15.0 are not affected, because StreamReadConstraints -- which defines the maxNumberLength setting -- was first introduced in jackson-core 2.15.0, so no such constraint exists to be bypassed in earlier releases. Note that GHSA-72hv-8253-57qq records the lower bound of the affected 2.x range as 2.0.0.

Patch / fix

  • maven tools.jackson.core:jackson-core 3.1.0
  • maven com.fasterxml.jackson.core:jackson-core 2.18.6, 2.21.1
  • FasterXML jackson-core 2.18.6, 2.21.1, 3.1.0
  • jackson-databind SLES for SAP applications 16.0, SLES 16.0 2.18.11-160000.1.1
  • jackson-core SLES for SAP applications 16.0, SLES 16.0 2.18.11-160000.1.1
  • jackson-annotations SLES for SAP applications 16.0, SLES 16.0 2.18.11-160000.1.1
  • jackson-core SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.11-150200.3.30.1
  • jackson-databind SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.11-150200.3.36.1
  • jackson-annotations SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.11-150200.3.28.1
  • jackson-dataformat-xml SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.11-150200.5.8.1
  • jackson-dataformats-binary SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.11-150200.3.29.1

suse advisories SUSE-SU-2026:24149-1SUSE-SU-2026:4394-1

  • jackson-databind openSUSE Leap 16.0 2.18.11-160000.1.1
  • jackson-core openSUSE Leap 16.0 2.18.11-160000.1.1
  • jackson-annotations openSUSE Leap 16.0 2.18.11-160000.1.1
  • jackson-core openSUSE Tumbleweed 2.18.9-2.1

opensuse advisories openSUSE-SU-2026:22034-1openSUSE-SU-2026:11638-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-18401 updated cvss 5.3

tools.jackson.core/jackson-core: com.fasterxml.jackson.core/jackson-core: jackson-core: Denial of Service due to number length bypass in asynchronous JSON parser

  • Red Hat OpenShift Developer Tools and Services jenkins 2.516.3.1758206866-3.el9, jenkins-2-plugins 4.19.1758207171-1.el9
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenShift Serverless openshift-serverless-1/kn-ekb-receiver-rhel9, openshift-serverless-1/kn-ekb-dispatcher-rhel9, openshift-serverless-1/kn-eventing-integrations-log-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-s3-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-sns-sink-rhel9, openshift-serverless-1/kn-eventing-integrations-aws-sqs-sink-rhel9, +4 more Red Hat AMQ Clients jackson-core 2.21.2.redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Ansible Automation Platform 2 ansible-automation-platform-25/de-minimal-rhel8, ansible-automation-platform-25/de-minimal-rhel9, ansible-automation-platform-26/de-minimal-rhel9, python3.11-drools-jpy-jar 1.0.7-1.Final_redhat_00001.1.el9ap, python3.12-drools-jpy-jar 1.0.7-2.Final_redhat_00001.1.el9ap
    affected: workaround, no fix available, no fix planned “Out of support scope”
  • Red Hat build of Apache Camel for Spring Boot 4 rhaf-camel-maven-repository.zip 4.18.1.ER9, rhaf-camel-for-springboot-maven-repository.zip 4.18.1, rhaf-camel-spring-boot-maven-repository.zip 4.18.1.CS4
    affected: workaround, no fix available “Fix deferred”
  • Red Hat build of Apicurio Registry 3 jackson-core 2.21.2.redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat build of Debezium 3 debezium-server.zip 3.4.3.CR4, debezium-maven-repository.zip 3.4.3.CR4
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Build of Keycloak rhbk-rhel9-operator, rhbk-openshift-rhel9 Red Hat build of Quarkus jackson-core 2.21.2.redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Certificate System 11 redhat-pki 11.10.0-1.el10_2
    affected: workaround, no fix available “Fix deferred”
show 9 more
  • Red Hat JBoss Enterprise Application Platform 7 eap74-els-openjdk8-openshift-rhel8, eap74-els-openjdk11-openshift-rhel8, eap74-els-openjdk17-openshift-rhel8, jboss-eap-7-eap74-els-openjdk11-openshift-rhel8, jboss-eap-7-eap74-els-openjdk17-openshift-rhel8
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat JBoss Enterprise Application Platform 8 jboss-eap-runtime-maven-repository.zip, jboss-eap.1-runtime-maven-repository.zip 8.1.0 Red Hat JBoss Enterprise Application Platform Expansion Pack jackson-core 2.21.2.redhat-00001 Red Hat JBoss Web Server 7 jws70-openjdk17-rhel9-openshift, jws70-openjdk21-rhel9-openshift, jboss-webserver-7-jws70-openjdk17-openshift-rhel9, jboss-webserver-7-jws70-openjdk21-openshift-rhel9 Red Hat Lightspeed for Runtimes Operator rh-lightspeed-runtimes/runtimes-agent-init-rhel9
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Offline Knowledge Portal offline-knowledge-portal/rhokp-rhel9
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-modelmesh-rhel9, rhoai/odh-vllm-gaudi-rhel9, rhoai/odh-spark-operator-rhel9, rhoai/odh-trustyai-service-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, +15 more
    affected: workaround, no fix available “Fix deferred”
  • Red Hat OpenShift Dev Spaces devspaces/server-rhel9, devspaces/openvsx-rhel9, devspaces/pluginregistry-rhel9, devspaces/multicluster-redirector-rhel9
    affected: workaround, no fix available, no fix planned “Out of support scope”
  • Red Hat Satellite 6 candlepin, candlepin-selinux, openvox-server 8.14.1-1.el9sat
    affected: workaround, no fix available “Fix deferred”
  • Red Hat streams for Apache Kafka 2 jackson-core 2.21.2.redhat-00001
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat streams for Apache Kafka 3 jackson-core 2.21.2.redhat-00001
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Cryostat 4 jackson-core 2.21.2.redhat-00001 Red Hat OpenShift Developer Tools and Services ocp-tools-4/jenkins-rhel8, ocp-tools-4/jenkins-rhel9 Red Hat AI Inference Server rhaii/vllm-gaudi-rhel9, rhaiis/vllm-cuda-rhel9 Red Hat AMQ Broker 7 amq-broker-bin.zip 7.14.1.CR1, amq-broker-maven-repository.zip 7.14.1.CR1 Red Hat Ansible Automation Platform 2 ansible-automation-platform-24/de-minimal-rhel8, ansible-automation-platform-24/de-minimal-rhel9, ansible-automation-platform-27/de-minimal-rhel9, ansible-automation-platform-27/de-supported-rhel9, python-drools-jpy-jar 1.0.6-1.Final_redhat_00001.1.el9ap, python3x-drools-jpy-jar 1.0.6-1.Final_redhat_00001.1.el8ap Red Hat build of Apache Camel - HawtIO 4 jackson-core 2.21.2.redhat-00001
    +11 more products
    Red Hat build of Apache Camel 4 for Quarkus 3 jackson-core 2.21.2.redhat-00001 Red Hat Build of Keycloak rhbk-keycloak-rhel9, rhbk-keycloak-rhel9-operator, rhbk-quarkus-dist.zip 26.6.4.CR2 Red Hat Certificate System 10 redhat-pki 11.9.2-4.module+el8pki+24565+7517ad63 Red Hat Data Grid 8 datagrid-datagrid-8-rhel9, redhat-datagrid-server.zip 8.6.2.CR1, redhat-datagrid-maven-repository.zip 8.6.1.CR1 Red Hat Enterprise Linux 8 jss, pki-ca, idm-jss, ldapjdk, pki-kra, pki-acme, +25 more Red Hat Enterprise Linux 9 pki-ca, pki-kra, pki-acme, pki-base, pki-core, pki-tools, +13 more Red Hat Enterprise Linux 10 dogtag-pki 11.6.0-2.el10_0 Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-gaudi-rhel9 Red Hat JBoss Enterprise Application Platform 7 jboss-eap-patch.zip, jboss-eap-maven-repository.zip, jboss-eap-full-maven-repository.zip, jboss-eap-runtime-maven-repository.zip, jboss-eap-incremental-maven-repository.zip Red Hat Satellite 6 puppetserver Red Hat Single Sign-On 7 jackson-core 2.21.2.redhat-00001
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/FasterXML/jackson-core/security/advisories/GHSA-72hv-8253-57qq referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
CNA 4.0 6.9 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/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

Affected packages

ecosystem package affected fixed in
maven tools.jackson.core:jackson-core
>=3.0.0, <3.1.0
3.1.0
maven com.fasterxml.jackson.core:jackson-core
>=2.19.0, <2.21.1
>=2.15.0, <2.18.6
2.21.1
2.18.6

Affected products

  • FasterXML jackson-core

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.