What is the CVSS score of CVE-2026-70436?

CVE-2026-70436 has a CVSS 3.1 base score of 4.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.1%.

Which versions of Jenkins are affected by CVE-2026-70436?

Jenkins versions 2.575 and earlier (LTS 2.568.1 and earlier) contain multiple critical remote code execution vulnerabilities affecting the CI/CD infrastructure trusted to build, test, and deploy…

How to fix or mitigate CVE-2026-70436?

Within 24 hours: Inventory all Jenkins deployments running version 2.575 or earlier (LTS 2.568.1 or earlier), audit which systems hold Agent/Connect permissions, and immediately restrict those permissions to only trusted operators and pre-approved systems while disabling unnecessary plugin features. Within 7 days: Implement network segmentation to isolate Jenkins controllers from untrusted networks, disable the Remoting library deserialization features and tar archive handling if operationally feasible, and configure audit logging and intrusion detection rules targeting deserialization attempts and path traversal operations. Within 30 days: Establish a vendor patch monitoring process for Jenkins security advisories, develop and test an upgrade plan to newer Jenkins versions once patches are released, and conduct a full security assessment of the CI/CD pipeline and any credentials exposed through the affected systems.

Jenkins CVE-2026-70436

EUVD-2026-53530 MEDIUM

Missing Authorization (CWE-862)

2026-08-05

GHSA-w8fh-xx7f-5j67

Jenkins Authentication Bypass

4.3

CVSS 3.1 · Vendor

Severity by source

Vendor (CNA) PRIMARY

4.3 MEDIUM

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

vuln.today AI

9.9 CRITICAL

Remoting bypass requires Agent/Connect (PR:L), is network-exploitable, crosses scope boundary to controller, yielding full RCE.

3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Primary rating from Vendor (CNA).

CVSS VectorVendor

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

Severity Changed

Aug 06, 2026 - 16:22 NVD

CRITICAL MEDIUM

CVSS changed

Aug 06, 2026 - 16:22 NVD

4.3 (CRITICAL) 4.3 (MEDIUM)

Analysis Generated

Aug 05, 2026 - 16:24 vuln.today

CVE Published

Aug 05, 2026 - 14:02 oss-security

CRITICAL

Description PRE-NVD

Disclosed via oss-security. NVD scoring and full description are pending.

Articles & Coverage 1

News Critical RCE via Deserialization Filter Bypass in Jenkins 2.575 - CVE-2026-70436 Aug 06, 2026

AnalysisAI

Jenkins 2.575 and earlier (LTS 2.568.1 and earlier) and multiple Jenkins plugins contain a cluster of vulnerabilities ranging from remote code execution via deserialization filter bypass to path traversal, CSRF, permission check failures, and Unicode-based user impersonation. The most critical issue - a bypass of the JEP-200 class filter in the Remoting library - allows authenticated agent operators or principals holding Agent/Connect permission to execute arbitrary code on the Jenkins controller. Three separate avenues for controller-side code execution are present in this advisory: the Remoting deserialization bypass (CVE-2026-70426), a tar archive symlink path traversal (CVE-2026-70427), and a file parameter path traversal (CVE-2026-70428). No public exploit or CISA KEV listing is confirmed at time of analysis, but the severity and variety of attack paths make this advisory high-priority for any Jenkins deployment.

Technical ContextAI

Jenkins uses the Remoting library (agent.jar/remoting.jar) for serialized Java object communication between the controller and agents. JEP-200 defines a class allowlist/denylist enforced during deserialization to prevent classic Java deserialization attacks; the vulnerability in Remoting 3384.v60d89463d9e0 and earlier (except the backport branch 3355.3357.v931d3c992987) exposes a fallback deserialization path that bypasses this filter for classes on the Jenkins core classpath. The tar archive issue stems from improper handling of symbolic links with effectively empty names during archive extraction - a well-known class of path traversal defect. The file parameter path traversal (CWE class: improper path neutralization) allows project configurators to write to arbitrary controller file system locations. The Unicode case-folding issue arises from a mismatch between ID canonicalization (lowercase via String#toLowerCase) and comparison logic (String#equalsIgnoreCase), which treats certain non-ASCII characters such as the dotless-i (ı) as equivalent to ASCII counterparts - a known Java internationalization pitfall. The Multijob Plugin's Groovy execution flaw occurs because it does not route scripts through the Jenkins Script Security Plugin, bypassing the sandbox and allowing direct JVM-level code execution.

RemediationAI

Upgrade Jenkins core to version 2.576 (weekly) or Jenkins LTS 2.568.2 to address all core vulnerabilities (CVE-2026-70426 through CVE-2026-70430). For plugin-level fixes, upgrade Multijob Plugin to 677.v7ffc23d6a_4c2, HCL AppScan Plugin to 1.8.4, External Workspace Manager Plugin to 1.4.2, SCM-Manager Plugin to 1.12.1, and Webhook Secret Credentials Provider Plugin to 32.v09c9b_522f0a_8. For the eleven plugins with unresolved security issues (AWS CodeBuild, CodeSonar, Google Chat Notification, Horreum, Ivy Report, Parameterized Remote Trigger, Qualys Container Scanning Connector, Sauce OnDemand, Summary Display, Violation Comments to GitLab, XML Job to Job DSL), no vendor patch is available at time of advisory publication; mitigations include disabling or removing these plugins, restricting access to the relevant Jenkins endpoints, and applying the principle of least privilege to agent and project permissions. For the Remoting deserialization bypass specifically, restricting Agent/Connect permission to only fully trusted principals reduces the attack surface until patching is complete. The full advisory and specific plugin advisory links are at https://www.jenkins.io/security/advisory/2026-08-05/.