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HIGH severity

CVE-2026-53435 — jenkins-core

HIGHFix: jenkinsci/jenkins@d739f6a

CVE-2026-53435 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability in org.jenkins-ci.main:jenkins-core. 1 public exploit reference exists, so weaponization risk is real. A fix is available for org.jenkins-ci.main:jenkins-core — see the affected versions and patch details below.

Jenkins arbitrary type deserialization from attacker-controlled config.xml allows remote code execution and user impersonation

Also known asBIT-jenkins-2026-53435GHSA-g2xq-2v27-4rh3
Published
Jun 10, 2026
Updated
Aug 28, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
1 known
Exploitation data as of Sep 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-53435.

EPSS Exploitation Probability

via FIRST.org ↗
2.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs81th percentile — riskier than 81% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2026-53435 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 380,066 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected
☕org.jenkins-ci.main:jenkins-core☕org.jenkins-ci.main:jenkins-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

In Jenkins 2.567 and earlier, LTS 2.555.2 and earlier, it is possible for attackers to have Jenkins deserialize arbitrary types defined in Jenkins core or plugins from an attacker-controlled config.xml submission in a way that allows them to handle HTTP requests afterwards. This can be used to impersonate any user and send HTTP requests on their behalf, up to and including use of the Script Console to run arbitrary code, or to read arbitrary files from the Jenkins controller.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.jenkins-ci.main:jenkins-coreall versions2.555.3org.jenkins-ci.main:jenkins-core:2.555.3
☕Mavenorg.jenkins-ci.main:jenkins-core≥ 2.556&&< 2.5682.568org.jenkins-ci.main:jenkins-core:2.568

Affected Products

1 product · 2 configurations
Application
jenkinsjenkins
< 2.568
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

AmesianX/CVE-2026-53435

An offensive security researcher + an AI vs. a fresh n-day: building the

⭐ 11🍴 4Aug 2026

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.jenkins-ci.main:jenkins-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.jenkins-ci.main:jenkins-core to 2.555.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-53435 is resolved across your whole dependency graph.

  3. Workarounds

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatImportant
ProductFixed inAdvisory
OpenShift Developer Tools and Services 4.12ocp-tools-4/jenkins-rhel8:1786628667RHSA-2026:60247
OpenShift Developer Tools and Services 4.13ocp-tools-4/jenkins-rhel8:1786628681RHSA-2026:60249
OpenShift Developer Tools and Services 4.14ocp-tools-4/jenkins-rhel8:1786533561RHSA-2026:60248
OpenShift Developer Tools and Services 4.15ocp-tools-4/jenkins-rhel8:1786533565RHSA-2026:60239
OpenShift Developer Tools and Services 4.16ocp-tools-4/jenkins-rhel9:1787125166RHSA-2026:60251
OpenShift Developer Tools and Services 4.17ocp-tools-4/jenkins-rhel9:1787124635RHSA-2026:60246
OpenShift Developer Tools and Services 4.18ocp-tools-4/jenkins-rhel9:1787125069RHSA-2026:60250
OpenShift Developer Tools and Services 4.19ocp-tools-4/jenkins-rhel9:1787124632RHSA-2026:60252

Frequently Asked Questions

In Jenkins 2.567 and earlier, LTS 2.555.2 and earlier, it is possible for attackers to have Jenkins deserialize arbitrary types defined in Jenkins core or plugins from an attacker-controlled `config.xml` submission in a way that allows them to handle HTTP requests afterwards. This can be used to impersonate any user and send HTTP requests on their behalf, up to and including use of the Script Console to run arbitrary code, or to read arbitrary files from the Jenkins controller.
O3 Security · Impact-Aware SCA

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CVE-2026-53435: jenkins-core RCE (High 8.8) | O3 Security