Exploited. On CISA's list since 2022-02-10.

Jenkins Stapler Web Framework Deserialization of Untrusted Data Vulnerability

CVE-2018-1000861 · Jenkins Jenkins Stapler Web Framework · Published 2018-12-10

How bad would it be?

9.8 out of 10

CVSS rates it critical: about as damaging as flaws get.

How likely is it to be used?

98%

Estimated chance of exploitation in the next 30 days, among the top 1% of all scored flaws (EPSS, 2026-10-29).

Is it already being used?

Yes

CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 1542 days ago (2022-08-10).

What CISA says to do

Apply updates per vendor instructions.

A code execution vulnerability exists in the Stapler web framework used by Jenkins

nvd.nist.gov

What the flaw is

A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153 and earlier, LTS 2.138.3 and earlier in stapler/core/src/main/java/org/kohsuke/stapler/MetaClass.java that allows attackers to invoke some methods on Java objects by accessing crafted URLs that were not intended to be invoked this way.

From the NVD.

Fixes and advisories

jenkins.ioVendor Advisory
jenkins.ioVendor Advisory

Learn this

Explore this week’s weaknesses and all learning topics

Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.

Insecure deserialization

Rebuilding objects from untrusted saved data can trigger unintended behaviour.

CWE-502 · CISA KEV; NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0; NVD record: nvd@nist.gov

Reading and practice labs · Free account for labs. Basic HTTP knowledge; some labs use Burp Suite.

Explore the labs at PortSwigger Web Security Academy How it is prevented

CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.

On SentryFeed

No story in the last 14 days has mentioned it.

Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.