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Fencer Intel
medium 5.3

CVE-2021-26085 kev+ ransomware in the critical feed json

Affected versions of Atlassian Confluence Server allow remote attackers to view restricted resources via a Pre-Authorization Arbitrary File…

published 5y ago modified 4mo ago also EUVD-2021-12906

cvss
5.3
version 3.1, CNA
cisa kev
Exploited
added 2022-03-28, used in ransomware
epss
99.9%
EPSS 99.9% chance of exploitation in 30 days, percentile 99.9%
public exploits
1
Exploit-DB, plus a Nuclei check

Summary

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.

Patch / fix

cisa required action Apply updates per vendor instructions.

  • Atlassian Confluence Server 7.4.10, 7.12.3
  • Atlassian Confluence Data Center 7.4.10, 7.12.3

Is CVE-2021-26085 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Timeline

  1. Published
  2. First public exploit (EDB-50377)
  3. Added to CISA KEV
  4. CISA patch deadline
  5. CISA SSVC: exploitation active

Known exploited

Added
4y ago
Patch by
2022-04-18 (4y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply updates per vendor instructions.
Vendor, product
Atlassian, Confluence Server
CISA name
Atlassian Confluence Server Pre-Authorization Arbitrary File Read Vulnerability

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1190 Exploit Public-Facing Application exploitation
  • T1005 Data from Local System primary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
partial
Assessed
last yr.

Exploit prediction

99.94% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • EDB-50377 Atlassian Confluence 7.12.2 - Pre-Authorization Arbitrary File Read webapps, 2021-10-05
  • Nuclei template Atlassian Confluence Server - Local File Inclusion nuclei detection template
  • packetstormsecurity.com http://packetstormsecurity.com/files/164401/Atlassian-Confluence-Server-7.5.1-Arbitrary-File-Read.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • Atlassian Confluence Server
  • Atlassian Confluence Data Center

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.