How severe is CVE-2018-1999042?

CVE-2018-1999042 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2018-1999042?

CVE-2018-1999042 affects the following packages: org.jenkins-ci.main:jenkins-core (Maven), org.jenkins-ci.main:jenkins-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2018-1999042?

Update org.jenkins-ci.main:jenkins-core to 2.121.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1999042 is resolved across your whole dependency graph.

How do I detect CVE-2018-1999042 in my Maven dependencies?

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.

How do I mitigate CVE-2018-1999042 if there is no patch (or I can't update yet)?

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.

Is CVE-2018-1999042 actively exploited in the wild?

No public exploit code has been indexed for CVE-2018-1999042 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2018-1999042?

CVE-2018-1999042 has an EPSS (Exploit Prediction Scoring System) score of 1.5%, placing it in the 74th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2018-1999042?

CVE-2018-1999042 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2018-1999042 published, and has it been updated?

CVE-2018-1999042 was published on August 23, 2018 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

MEDIUM severity

CVE-2018-1999042 — jenkins-core

MEDIUMFix: jenkinsci/jenkins@727d58f

CVE-2018-1999042 is a medium-severity (CVSS 5.3) Deserialization of Untrusted Data vulnerability in org.jenkins-ci.main:jenkins-core. A fix is available for org.jenkins-ci.main:jenkins-core — see the affected versions and patch details below.

Deserialization of Untrusted Data in Jenkins

Also known asGHSA-28p3-mchr-9frj

Published

Aug 23, 2018

Updated

Oct 24, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk

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

How urgent is this, really

Where this sits among everything scored

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

A vulnerability exists in Jenkins 2.137 and earlier, 2.121.2 and earlier in XStream2.java that allows attackers to have Jenkins resolve a domain name when deserializing an instance of java.net.URL.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.jenkins-ci.main:jenkins-core`	all versions	2.121.3`org.jenkins-ci.main:jenkins-core:2.121.3`
☕Maven	`org.jenkins-ci.main:jenkins-core`	≥ 2.122&&< 2.138	2.138`org.jenkins-ci.main:jenkins-core:2.138`

Affected Products

1 product · 2 configurations

Application

jenkinsjenkins

≤ 2.137

range

Detection & mitigation playbook

Open-source dependency

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.
Fix
Update org.jenkins-ci.main:jenkins-core to 2.121.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2018-1999042 is resolved across your whole dependency graph.
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.

Frequently Asked Questions

A vulnerability exists in Jenkins 2.137 and earlier, 2.121.2 and earlier in XStream2.java that allows attackers to have Jenkins resolve a domain name when deserializing an instance of java.net.URL.

O3 Security · Impact-Aware SCA

Is CVE-2018-1999042 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

5.3/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Raw vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

CWE Classification

CWE-502Deserialization of Untrusted Data

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

jenkins

6.4/10

Code-Review6/10

Maintained10/10

Branch-Protection3/10

Assessed Oct 26, 2026

Timeline

Disclosed

Aug 23, 2018

Last updated

Oct 24, 2026

Identifiers

CVE-2018-1999042

GHSA-28p3-mchr-9frj

References

Advisoryjenkins.io · 2018 08 15 Advisorynvd.nist.gov · CVE 2018 1999042 Webgithub.com · 727d58f690abf64f543407e1de3545eca76ad30e Packagegithub.com · jenkins

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs affecting jenkins-core are rated as high or higher (top: high).

CVE-2026-53436CVE-2026-53437CVE-2026-53440CVE-2026-53441CVE-2026-53439CVE-2026-53435CVE-2026-53442CVE-2026-53438

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 24, 2026

CVE-2018-1999042 — jenkins-core

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2018-1999042 in your dependencies?