What is the CVSS score of CVE-2021-21371?

CVE-2021-21371 has a CVSS 3.1 base score of 8.6 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.5%.

Is there a patch available for CVE-2021-21371?

Yes, a patch is available for CVE-2021-21371. Update the affected software to the latest version immediately.

Jira Cloud CVE-2021-21371

HIGH

Deserialization of Untrusted Data (CWE-502)

2021-03-10 security-advisories@github.com

RCE Deserialization Atlassian Jira Cloud Tenable

8.6

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-502 OWASP Top 10:2025 A08:2025 - Software or Data Integrity Failures ASVS 5.0 V1 - Encoding and Sanitization Safe deserialization, type allowlists MITRE ATT&CK 2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 8.6 (HIGH). Attack characteristics: local attack vector, low complexity, no privileges required, user interaction required.
Exploit ScenarioDerived	A local attacker with access to the system could execute arbitrary code through malicious serialized objects. No authentication is required to exploit this vulnerability.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

Patch available 0.5% exploitation probability (EPSS)

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AnalysisAI

Tenable for Jira Cloud is an open source project designed to pull Tenable.io vulnerability data, then generate Jira Tasks and sub-tasks based on the vulnerabilities' current state. Rated high severity (CVSS 8.6), this vulnerability is no authentication required, low attack complexity. This Deserialization of Untrusted Data vulnerability could allow attackers to execute arbitrary code through malicious serialized objects.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Avoid deserializing untrusted data. Use safe serialization formats (JSON). Implement integrity checks and type allowlists.

Affected Packages

pypi tenable-jira-cloud fix: 1.1.21, 1.1.22

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in pypi

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Deserialization of Untrusted Data (CWE-502), which allows attackers to execute arbitrary code through malicious serialized objects. Tenable for Jira Cloud is an open source project designed to pull Tenable.io vulnerability data, then generate Jira Tasks and sub-tasks based on the vulnerabilities' current state. It published in pypi as "tenable-jira-cloud". In tenable-jira-cloud before version 1.1.21, it is possible to run arbitrary commands through the yaml.load() method. This could allow an attacker with local access to the host to run arbitrary code by running the application with a specially crafted YAML configuration file. This is fixed in version 1.1.21 by using yaml.safe_load() instead of yaml.load(). Affected products include: Tenable Jira Cloud. Version information: version 1.1.21.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.6 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Local

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

Tenable for Jira Cloud is an open source project designed to pull Tenable.io vulnerability data, then generate Jira Tasks and sub-tasks based on the vulnerabilities' current state. It published in pypi as "tenable-jira-cloud". In tenable-jira-cloud before version 1.1.21, it is possible to run arbitrary commands through the yaml.load() method. This could allow an attacker with local access to the host to run arbitrary code by running the application with a specially crafted YAML configuration file. This is fixed in version 1.1.21 by using yaml.safe_load() instead of yaml.load().

Threat Intelligence Overview

EPSS Score

0.5%

Top 64% exploitable

Data Quality

3 sources

Confidence: Low

NVD

CVE.org

EPSS

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 0.5%

Patch available Yes

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Small

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +43

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Insecure Deserialization CRITICAL

Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.

Remote Code Execution CRITICAL

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.