Bitbucket CVE-2023-34453 Impact and Mitigation Steps:

• • Severity: The critical vulnerability in Atlassian Bitbucket Data Center, Bitbucket Server is classified as “HIGH”
  • Versions Impacted: 7.21.0, 7.21.1, 7.21.2, 7.21.3, 7.21.4, 7.21.5, 7.21.6, 7.21.7, 7.21.8, 7.21.9, 7.21.10, 7.21.11, 7.21.12, 7.21.13, 8.7.0, 8.8.0, 8.9.0, 8.9.1, 8.9.2, 8.10.0, 8.10.1, 8.10.2, 8.11.0, 8.11.1, 8.12.0, 8.9.3, 8.10.3, 8.11.2, 7.21.14, 7.21.15, 8.9.4, 8.10.4, 8.11.3, 8.12.1, 8.13.0, 7.21.16, 7.21.17, 7.21.18
  • Vulnerability Type: Public Security Vulnerability
  • CVE Identifier: The specific vulnerability is tracked as CVE-2023-34453
  • CVSS Score: Atlassian assigned a CVSS score of 7.5 to this vulnerability, highlighting its severity. 
  • Vulnerability Class: DoS (Denial of Service)
  • Affected Products: Bitbucket Data Center, Bitbucket Server
  • This High severity vulnerability was introduced in versions 7.21.0, 8.9.0 and 8.13.0 of Bitbucket Data Center and Server.
  • This vulnerability allows an unauthenticated attacker to expose assets in your environment susceptible to exploitation which has no impact to confidentiality, no impact to integrity, high impact to availability, and requires no user interaction.

Affected Versions:

• Versions Impacted: 7.21.0, 7.21.1, 7.21.2, 7.21.3, 7.21.4, 7.21.5, 7.21.6, 7.21.7, 7.21.8, 7.21.9, 7.21.10, 7.21.11, 7.21.12, 7.21.13, 8.7.0, 8.8.0, 8.9.0, 8.9.1, 8.9.2, 8.10.0, 8.10.1, 8.10.2, 8.11.0, 8.11.1, 8.12.0, 8.9.3, 8.10.3, 8.11.2, 7.21.14, 7.21.15, 8.9.4, 8.10.4, 8.11.3, 8.12.1, 8.13.0, 7.21.16, 7.21.17, 7.21.18

Recommended Actions:

• • Atlassian recommends that Bitbucket Data Center and Server customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions:
    • Bitbucket Data Center and Server 7.21: Upgrade to a release greater than or equal to 7.21.21
    • Bitbucket Data Center and Server 8.9: Upgrade to a release greater than or equal to 8.9.5
    • Bitbucket Data Center and Server 8.13: Upgrade to a release greater than or equal to 8.13.1
  • Release notes can be found here (https://confluence.atlassian.com/bitbucketserver/release-notes). You can download the latest version of Bitbucket Data Center and Server from the download center (https://www.atlassian.com/software/bitbucket/download-archives).

Standard Manual Upgrade Steps:

• • Notify users of outage for critical hotfixing
  • Stop services across all nodes
  • Backup existing database and shared home prior to upgrade
  • Make copies of the setenv.sh and server.xml found in the application install directories bin & conf (these hold critical settings we want to propogate again post upgrade
  • Download the hotfix from the Atlassian archives
  • Apply the upgrade, do not auto-start services
  • Copy back the setenv.sh, server.xml, and any other customized files you had to copy during the upgrade process
  • Restart services and perform smoke testing once the Software  is available

Conclusion:

The advisory regarding the critical DoS (Denial of Service), CVE-2023-34453, in Bitbucket Data Center, Bitbucket Server is of utmost importance. With a CVSS score of 7.5 , this vulnerability poses a significant threat, allowing unauthenticated attackers to potentially compromise Bitbucket Servers. 

To safeguard their systems and prevent the potential leakage of sensitive information and malicious attacks, all users are recommended to upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions. 

Here is the notice from the National Vulnerability Database

Link to Atlassian ticket can be found here. 

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