CVE-2021-39125Network attack vector

Unauthenticated username enumeration via password reset

Published Sep 14, 2021 · Updated Oct 9, 2024

Username enumeration in Atlassian Jira Server and Data Center before 8.5.10 and 8.6.0 through 8.13.0 allows remote attackers to discover usernames. Atlassian identifies the password reset page as the locus but has not published the response difference or code path that reveals account validity. No authentication is required, and the disclosed consequence is limited to collecting valid usernames.

CVSS severity5.3
Medium
EPSS probability1.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Username enumeration in Atlassian Jira Server and Data Center before 8.5.10 and 8.6.0 through 8.13.0 allows remote attackers to discover usernames. Atlassian identifies the password reset page as the locus but has not published the response difference or code path that reveals account validity. No authentication is required, and the disclosed consequence is limited to collecting valid usernames.

The record

CVE
CVE-2021-39125
Published
Sep 14, 2021
Updated
Oct 9, 2024
Vendor
Atlassian
Product
Jira Server
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 14, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 9, 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 <8.5.10
  2. Affected versionversion=8.6.0 <8.13.1
  3. Affected versionversion=8.6.0 <unspecified
  4. Affected versionversion=unspecified <8.13.1
  5. Affected versionversion=unspecified <8.5.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Atlassian · Jira Serverversion=0 <8.5.10; version=8.6.0 <8.13.1; version=8.6.0 <unspecified; version=unspecified <8.13.1; version=unspecified <8.5.10
Atlassian · Jira Data Centerversion=0 <8.5.10; version=8.6.0 <8.13.1; version=8.6.0 <unspecified; version=unspecified <8.13.1; version=unspecified <8.5.10

Published CVSS scores

5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N

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

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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