CVE-2024-21661Public exploitNetwork attack vector

API server crash via unsynchronized failed-login map

Published Mar 18, 2024 · Updated Aug 2, 2024

Denial of service in affected Argo CD releases allows remote attackers to crash the API server through concurrent failed-login requests. The expireOldFailedAttempts function deletes entries from the shared failed-login map while concurrent VerifyUsernamePassword calls update it without synchronization. Unauthenticated network access is sufficient, and repeated triggering can keep the application unavailable to legitimate users.

CVSS severity7.5
High
EPSS probability1.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in affected Argo CD releases allows remote attackers to crash the API server through concurrent failed-login requests. The expireOldFailedAttempts function deletes entries from the shared failed-login map while concurrent VerifyUsernamePassword calls update it without synchronization. Unauthenticated network access is sufficient, and repeated triggering can keep the application unavailable to legitimate users.

The record

CVE
CVE-2024-21661
Published
Mar 18, 2024
Updated
Aug 2, 2024
Vendor
Argo Project
Product
Argo CD
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <2.8.13
  2. Affected versionversion=>= 2.10.0, < 2.10.4
  3. Affected versionversion=2.10.0 <2.10.4
  4. Affected versionversion=< 2.8.13
  5. Affected versionversion=>= 2.9.0, < 2.9.9
  6. Affected versionversion=2.9.0 <2.9.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Argo Project · Argo CDversion=0 <2.8.13; version=>= 2.10.0, < 2.10.4; version=2.10.0 <2.10.4; version=< 2.8.13; version=>= 2.9.0, < 2.9.9; version=2.9.0 <2.9.9

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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