What’s Vulnerable › Vulnerabilities

CVE-2021-27890

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 10.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2021-03-15 · updated 2026-06-17
• Weakness: CWE-89

Description

SQL Injection vulnerablity in MyBB before 1.8.26 via theme properties included in theme XML files.

Affected products

• mybb: before 1.8.26 — fixed in 1.8.26

How to fix

Upgrade to a fixed version: mybb 1.8.26. Check the vendor advisory for mitigations.

References

• http://packetstormsecurity.com/files/161908/MyBB-1.8.25-Remote-Command-Execution.html
• https://blog.sonarsource.com/mybb-remote-code-execution-chain
• https://github.com/mybb/mybb/security/advisories/GHSA-r34m-ccm8-mfhq
• http://packetstormsecurity.com/files/161908/MyBB-1.8.25-Remote-Command-Execution.html
• https://blog.sonarsource.com/mybb-remote-code-execution-chain
• https://github.com/mybb/mybb/security/advisories/GHSA-r34m-ccm8-mfhq

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