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Atlassian Multiple Products Files or Directories Accessible to External Parties Vulnerability

Exploited · KEV 2026-10-15CVE-2026-21589CWE-552

Exploited since 2026-10-15. 3 of 8 rule sources name it; Cloudflare blocks by default. Our CRS test: not blocked.

Edge rules
3/8
Our test
Not blocked
CVSS
9.3
EPSS
99.5% Top 0.1%
Posts, 14d
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Published
2026-10-05
This is a vulnerability in Bitbucket Data Center, Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center. Crowd Data Center, Crucible and Fisheye. This Arbitrary File Access vulnerability… More

This is a vulnerability in Bitbucket Data Center, Confluence Data Center, Jira Service Management Data Center, Jira Software Data Center, Bamboo Data Center. Crowd Data Center, Crucible and Fisheye. This Arbitrary File Access vulnerability allows an unauthenticated attacker to access specific files within the web application root directory in affected versions. Exploitation requires prior knowledge of the target file's exact name and path; this vulnerability does not allow attackers to enumerate or list directory contents. In some configurations, there may be some sensitive files that make this highly severe. This vulnerability allows an unauthenticated remote attacker to access specific files within the web application root directory in affected versions. The vulnerability must be addressed for affected versions of: -- Bitbucket Data Center, introduced in version >= 4.6.0, fix versions: 9.4.26, 10.2.8, 10.5.1 -- Confluence Data Center, introduced in version >= 5.10.0, fix versions 9.2.26, 10.2.19 -- Crowd Data Center, introduced in version >= 2.11.0, fix versions 6.3.7, 7.0.3, 7.1.7, 7.2.4 -- Jira Software Data Center, introduced in version >= 7.1.0, fix versions 9.12.40, 10.3.26, 11.3.12 -- Jira Service Management Data Center, introduced in version >= 3.1.0, fix versions 5.12.40, 10.3.26, 11.3.12 -- Bamboo Data Center >= 7.0.1, fix versions 10.2.24, 12.1.12 -- Crucible, fix versions 4.9.15 -- Fisheye, fix version 4.9.15 -- Exploitation requires prior knowledge of the target file's exact name and path. The vulnerability does not include the capability to enumerate or list directory contents.

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Severity, decoded

CVSS 4.0
Critical · 9.3 / 10

Exploitable over the network, with no privileges and no user interaction, leading to full loss of confidentiality; other systems can also be hit (full loss of confidentiality, integrity and availability).

Over the internetNo login neededNo user actionWorks reliablySpreads beyond the appSerious impact
How the score is built11 metrics
  • Attack vectorAn attacker can reach it over the internet; no access to your network needed.
    Network
  • Attack complexityNo built-in defences have to be bypassed; the attack works reliably.
    Low
  • Attack requirementsThe attack works without any special deployment or timing conditions.
    None
  • Privileges requiredNo account or login is needed.
    None
  • User interactionNo one has to click or open anything; the attack works on its own.
    None
  • Confidentiality impact (vulnerable system)An attacker can read all data the affected component holds, or the most sensitive parts of it.
    High
  • Integrity impact (vulnerable system)Data cannot be changed by the attacker.
    None
  • Availability impact (vulnerable system)The component keeps working normally.
    None
  • Confidentiality impact (other systems)Other systems that rely on it can have all their data read.
    High
  • Integrity impact (other systems)Other systems that rely on it can have any data changed.
    High
  • Availability impact (other systems)Other systems that rely on it can be taken down.
    High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:H/SA:H
CISA's assessmentSSVC, from the CVE record
ExploitationActive

Attackers are exploiting this in the wild.

AutomatableNo

At least one step needs hands-on work, which slows mass attacks.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

1 found
0 Metasploit0 Exploit-DB1 Scanner template0 GitHub PoCs

Links are to third-party code: never run it outside an isolated lab.

Timeline

  1. 2026-10-05
    CVE published
    CVE List
  2. 2026-10-07
    Fastly ships a rule
    Added virtual patch for CVE-2026-21589 (Pre-Auth Arbitrary File Read in Multiple Atlassian Products)
  3. 2026-10-12
    Cloudflare ships a rule
    Atlassian - Arbitrary File Access - CVE:CVE-2026-21589
  4. 2026-10-15
    Added to CISA KEV
    Confirmed exploitation in the wild
  5. 2026-10-21
    F5 ships a rule
    Atlassian Bitbucket Data Center Arbitrary File Read
  6. 2026-11-02
    Our test: OWASP Core Rule Set let it through
    paranoia level 1, anomaly threshold 5, default CRS settings
  7. 2026-11-02
    Our test: OWASP Core Rule Set let it through
    paranoia level 2, anomaly threshold 5, default CRS settings

Social

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No posts seen yet on X, Bluesky, Mastodon, Hacker News or GitHub.

Vendor statements

Quoted
CloudflareWAF Managed Rules1 quoteBlocks by default

First rule 2026-10-12, 7 days after the CVE was published.

2026-10-12New rule…e919cd31Default: BlockSource
Atlassian - Arbitrary File Access - CVE:CVE-2026-21589. Previous action: N/A. New action: Block. This is a new detection.
AWSAWS WAF Managed RulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. AWS often describes a vulnerability without naming its CVE (for example "Log4j"). We count only entries that name the CVE, so AWS coverage is understated.

Microsoft AzureFront Door and Application Gateway WAF (DRS)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. The rule tables name CVEs but carry no dates, so Azure is left out of every time-to-rule figure.

Google CloudCloud Armor preconfigured WAF rulesNo public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. Google names few CVEs: the release notes start in May 2024 and the rules reference lists CVEs without dates. Its cve-canary rules are opt-in.

FastlyNext-Gen WAF virtual patches1 quoteRule published

First rule 2026-10-07, 2 days after the CVE was published.

2026-10-07New ruleSource
Added virtual patch for CVE-2026-21589 (Pre-Auth Arbitrary File Read in Multiple Atlassian Products). A pre-authorization arbitrary file read vulnerability has been found in multiple Atlassian products (e.g., Confluence, Jira, Bitbucket) and has been assigned CVE-2026-21589. Fastly has created a virtual patch for it that is now available within your account. To activate it and add protection to your services, follow the steps for your control panel below. Next-Gen WAF control panel From the Rul…
F5Attack signatures (Distributed Cloud WAF)1 quoteRule published

First rule 2026-10-21, 16 days after the CVE was published.

2026-10-21New rule200007125Source
Added: signature 200007125 "Atlassian Bitbucket Data Center Arbitrary File Read" (Path Traversal, risk High), systems: Java Servlets/JSP. References: CVE-2026-21589.
AkamaiApp & API Protector (Adaptive Security Engine)No public source

This vendor publishes no machine-readable rule changelog we can check.

OWASP CRSCore Rule Set (open source, used inside many WAFs)No public claim

We found no public statement from this vendor naming this CVE. That is not proof of no protection: generic rules may still catch it. CRS rarely names CVEs: it relies on generic detections. Our own lab measures what it actually blocks.