CVE-2024-21661: Argo CD Denial of Service (DoS) Vulnerability Due to Unsafe Array Modification in Multi-threaded Environment

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2024-03-18 · updated 2026-06-17
Weakness: CWE-787

Description

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. Prior to versions 2.8.13, 2.9.9, and 2.10.4, an attacker can exploit a critical flaw in the application to initiate a Denial of Service (DoS) attack, rendering the application inoperable and affecting all users. The issue arises from unsafe manipulation of an array in a multi-threaded environment. The vulnerability is rooted in the application's code, where an array is being modified while it is being iterated over. This is a classic programming error but becomes critically unsafe when executed in a multi-threaded environment. When two threads interact with the same array simultaneously, the application crashes. This is a Denial of Service (DoS) vulnerability. Any attacker can crash the application continuously, making it impossible for legitimate users to access the service. The issue is exacerbated because it does not require authentication, widening the pool of potential attackers. Versions 2.8.13, 2.9.9, and 2.10.4 contain a patch for this issue.

Affected products

argoproj argo-cd: before 2.8.13; from 2.9.0 before 2.9.9; from 2.10.0 before 2.10.4 — fixed in 2.10.4, 2.8.13, 2.9.9

How to fix

Upgrade to a fixed version: argoproj argo-cd 2.10.4, 2.8.13, 2.9.9. Check the vendor advisory for mitigations.

References

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