CVE-2021-39126Network attack vector

Resource modification via referrer-leaked CSRF token

Published Oct 21, 2021 · Updated Oct 10, 2024

CSRF in Atlassian Jira Server and Data Center before 8.5.10 and 8.6.0 through 8.13.0 allows remote attackers to modify resources. A referrer header discloses a user's CSRF token, which Jira then accepts to authorize forged state-changing requests. Exploitation requires user interaction and possession of the leaked token; the public record does not identify the resources that can be changed.

CVSS severity6.5
Medium
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

CSRF in Atlassian Jira Server and Data Center before 8.5.10 and 8.6.0 through 8.13.0 allows remote attackers to modify resources. A referrer header discloses a user's CSRF token, which Jira then accepts to authorize forged state-changing requests. Exploitation requires user interaction and possession of the leaked token; the public record does not identify the resources that can be changed.

The record

CVE
CVE-2021-39126
Published
Oct 21, 2021
Updated
Oct 10, 2024
Vendor
Atlassian
Product
Jira Server
Classifications
CWE-352
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Oct 10, 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=8.6.0 <unspecified
  2. Affected versionversion=unspecified <8.13.1
  3. Affected versionversion=unspecified <8.5.10

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

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

Published CVSS scores

4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N
6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/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

CWE-352Cross-Site Request Forgery (CSRF)

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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