CVE-2021-43958Network attack vector

Credential brute force via missing CAPTCHA enforcement

Published Mar 16, 2022 · Updated Oct 4, 2024

Improper authentication-attempt restriction in Atlassian FishEye and Crucible before 4.8.9 allows remote attackers to brute-force credentials. Affected REST resources accept authentication attempts without checking whether the user exceeded the failed-login limit and must solve a CAPTCHA. No account is required to submit guesses, and the bypass removes the CAPTCHA barrier after the configured limit.

CVSS severity9.8
Critical
EPSS probability1.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper authentication-attempt restriction in Atlassian FishEye and Crucible before 4.8.9 allows remote attackers to brute-force credentials. Affected REST resources accept authentication attempts without checking whether the user exceeded the failed-login limit and must solve a CAPTCHA. No account is required to submit guesses, and the bypass removes the CAPTCHA barrier after the configured limit.

The record

CVE
CVE-2021-43958
Published
Mar 16, 2022
Updated
Oct 4, 2024
Vendor
Atlassian
Product
FishEye
Classifications
CWE-307, T1110
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 16, 2022CVE publishedPublication date reported by the CVE source.
  2. Oct 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=0 <4.8.9
  2. Affected versionversion=unspecified <4.8.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Atlassian · FishEyeversion=0 <4.8.9; version=unspecified <4.8.9
Atlassian · Crucibleversion=0 <4.8.9; version=unspecified <4.8.9

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-307Improper Restriction of Excessive Authentication Attempts
T1110Brute Force

Public exploit references

No public exploit references are available in this record.

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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