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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 18 Apr 2022. Known ransomware use
Confluence Data CenterApplication · Atlassian

CVE-2021-26085

MEDIUM · 5.3 CVSS v3.1 Published 2021-08-03
Fix available
A fix is available. Upgrade to 7.4.10 / 7.12.3 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware High EPSS Public exploit Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Affected versions of Atlassian Confluence Server allow remote attackers to view restricted resources via a Pre-Authorization Arbitrary File Read vulnerability in the /s/ endpoint. The affected versions are before version 7.4.10, and from version 7.5.0 before 7.12.3.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Atlassian Confluence Server contains a pre-authorization arbitrary file read vulnerability in the /s/ endpoint. Attackers can exploit this vulnerability without authentication to read arbitrary files on the server, leading to information disclosure.

MitigationUpgrade Confluence Server to version 7.4.10, 7.12.3, or later to remediate this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Confluence Data CenterApplication
Affected:< 7.4.10>= 7.5.0, < 7.12.3
Confluence ServerApplication
Affected:< 7.4.10>= 7.5.0, < 7.12.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Determine installed Confluence version
    Access the Confluence administration dashboard and navigate to the General Configuration or Troubleshooting section to view the version number. Alternatively, check the confluence-version file in the Confluence installation directory.
    Affected if The installed version is less than 7.4.10 OR greater than or equal to 7.5.0 but less than 7.12.3
  2. Verify /s/ endpoint is accessible
    Send an unauthenticated HTTP request to the /s/ endpoint (for example: curl -I http://<confluence-host>/s/).
    Affected if The endpoint returns an HTTP 200 or other successful response without requiring authentication, indicating the vulnerable endpoint is exposed.
  3. Check Confluence Data Center vs Server
    Confirm whether the installation is Confluence Server or Confluence Data Center by reviewing the product type in the administration console or installation details.
    Affected if The product is Confluence Server or Confluence Data Center and the version falls within the affected ranges.

You are affected if your Confluence Server or Data Center version is less than 7.4.10 or falls between 7.5.0 and 7.12.3, and the /s/ endpoint is accessible without authentication.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 7.4.10 / 7.12.3 or later
Fixed in 7.4.107.12.3
Interim mitigation

Upgrade Confluence Server to version 7.4.10, 7.12.3, or later to remediate this vulnerability.

Recommended fix High confidence

Upgrade to Confluence 7.4.10 (for 7.4.x line) or Confluence 7.12.3 or later (for 7.5.0-7.12.x line)

  1. 1. Identify current Confluence version by checking the Confluence administration console or using the /confluence/aboutconfluence page
  2. 2. If running version < 7.4.10, plan upgrade to 7.4.10 or later in the 7.4.x LTS line
  3. 3. If running version >= 7.5.0 and < 7.12.3, plan upgrade to 7.12.3 or later in the 7.x line
  4. 4. Take a complete backup of the Confluence database and home directory before upgrading
  5. 5. Review Atlassian's upgrade documentation for your specific version path
  6. 6. Perform the upgrade in a staging environment first to validate compatibility
  7. 7. Apply the upgrade in production during a scheduled maintenance window
  8. 8. Verify the upgrade was successful and Confluence is functioning normally
Caveat Review Atlassian upgrade notes for potential breaking changes between versions; ensure database and plugins are compatible with target version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Confluence Data Center Exploited in the wild — priority engagement
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-26085 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data