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Vulnerabilities/CVE-2021-26085Public Intelligence Dossier
Source: atlassian · Limited verification•Last verified: •Collection Running
CVE-2021-26085ListedMEDIUM (raw)CVSS 5.3CWE-425

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

Published: 03 Aug 2021•Last updated: 17 Jun 2026, 09:12 AM IST•Source identifier: security@atlassian.com
Dossier completeness: source-provided sections 3 / 3 · rule guidance available. Missing source facts count as incomplete.
Official source
CISA KEV catalog
Listed
Added28 Mar 2022
Due18 Apr 2022
RansomwareKnown
CVSS score
5.3MEDIUM (raw)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Metric sourcenvd@nist.gov
EPSS probability
99.9%0.999
Percentile100th
Weakness type
CWE-425
No further CWE recorded
Remediation
Patch status unknown
No fixed version or KB recorded

Why It Matters

Analysis dossier

Why It Matters

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.

SOC priority

Immediate Attention

Actively exploited (source statement)

Yes

Publicly disclosed

Unknown

Risk basis: CISA KEV exploitation signal; Source-confirmed exploitation or CISA KEV/ransomware metadata

Affected Products & Remediation

2 source-backed products
Affected products and versions (source)
  • atlassian confluence data center · < 7.4.10; >= 7.5.0 < 7.12.3 · NVD CPE · Source
  • atlassian confluence server · < 7.4.10; >= 7.5.0 < 7.12.3 · NVD CPE · Source
Recorded patch / KBNot provided by source

Vendor or catalog guidance (source)

  • CISA KEV: Apply updates per vendor instructions.

Known exploitation (source facts)

Only what a source states. Unknown means no source has said either way; it is not "not exploited".

CISA KEV
Listed
Exploited (source statement)
Yes
Publicly disclosed (source)
Unknown

CISA required action: Apply updates per vendor instructions.

Suggested hunting (rule-based inference)

SecOps Signal recommendation (rule-based inference). These steps are hunting hypotheses from the vulnerability class; they do not state or imply that exploitation occurred here or anywhere.

Matched kev-network-exposure (CVSS AV:N, CISA KEV Listed); network-unauthenticated (CVSS AV:N, CVSS PR:N, CVSS UI:N)

Exposure

  1. Identify assets with the exact CVE and confirm the affected product/version against the advisory.Telemetry: DeviceTvmSoftwareVulnerabilities · KEV listing raises urgency, but inventory is needed to establish local exposure. · Rule kev-network-exposure
  2. Identify devices reporting this CVE and note which expose the affected service to untrusted networks.Telemetry: DeviceTvmSoftwareVulnerabilities · A network-reachable, no-privilege vector makes internet-facing instances the first exposure question. · Rule network-unauthenticated

Exploitation evidence

  1. Review relevant edge or application access logs for unusual requests around the advisory window.Telemetry: CommonSecurityLog · Log review is a hunting hypothesis; KEV listing alone does not show local exploitation. · Rule kev-network-exposure
Show more (2)

Exploitation evidence

  1. Review inbound connections to the affected service from unexpected sources since the advisory date.Telemetry: DeviceNetworkEvents · Hunting hypothesis from the CVSS vector; it does not show that exploitation occurred. · Rule network-unauthenticated

Response

  1. Recheck the affected assets after the source-stated mitigation or update is applied.Telemetry: DeviceTvmSoftwareVulnerabilities · A follow-up inventory check verifies local remediation. · Rule kev-network-exposure

CISA KEV Record

Catalog entry
28 Mar 2022
Required action due
18 Apr 2022
Known ransomware use
Known

Apply updates per vendor instructions.

Change History & Source Data

— No recorded material change

CNA / source
security@atlassian.com
Record status · verification
UPDATED · CISA KEV confirmed
CPE
cpe:2.3:a:atlassian:confluence_data_center:*:*:*:*:*:*:*:*, cpe:2.3:a:atlassian:confluence_server:*:*:*:*:*:*:*:*

Evidence & Provenance

4 public sources
CISA KEV CatalogAdded 2022-03-28jira.atlassian.comSource recordnvd.nist.govSource recordcisa.govSource record

Linked by the query's stored exact CVE association. Review required tables and validation status before use.

Detection Hunting Query
Target: DeviceTvmSoftwareVulnerabilities•Defender XDR
Detect endpoints exposed to CVE-2021-26085
Purpose: Exposure assessment (Category: Exposure Check)Why linked: Query metadata names CVE-2021-26085
DeviceTvmSoftwareVulnerabilities| where CveId == "CVE-2021-26085"| project DeviceId, DeviceName, OSPlatform, OSVersion, SoftwareVendor, SoftwareName, SoftwareVersion, CveId, VulnerabilitySeverityLevel, RecommendedSecurityUpdate, RecommendedSecurityUpdateId| sort by VulnerabilitySeverityLevel desc
Schema Checked · Not runtime validatedSource: SecOps Signal deterministic template · Limited verificationStatic screening: Passed structure and schema checks; tenant execution is not verified.
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Correlated briefings

SecOps Signal surfaces public advisory facts only. A missing value means the source has not published it, not that your environment is unaffected. No tenant inventory is connected.