CVE-2021-27890
CVE-2021-27890 is a high-severity vulnerability in Mybb with a CVSS 3.x base score of 8.8. Its EPSS exploit-prediction score of 11% places it in the 95th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-89.
Key facts
- Severity: High (CVSS 3.x base score 8.8)
- CVSS v2: 6.8
- EPSS exploit prediction: 11% (95th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-89
- Affected product: Mybb
- Published:
- Last modified:
Description
SQL Injection vulnerablity in MyBB before 1.8.26 via theme properties included in theme XML files.
Frequently asked questions
- What is CVE-2021-27890?
- SQL Injection vulnerablity in MyBB before 1.8.26 via theme properties included in theme XML files.
- How severe is CVE-2021-27890?
- CVE-2021-27890 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2021-27890 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 11% (95th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-27890?
- CVE-2021-27890 affects Mybb. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-27890?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2021-27890 published?
- CVE-2021-27890 was published on 2021-03-15 and last updated on 2026-06-17.
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
Affected products (1)
- cpe:2.3:a:mybb:mybb:*:*:*:*:*:*:*:*
More vulnerabilities in Mybb
- CVE-2015-8974 — Critical (CVSS 10.0): SQL injection vulnerability in the Group Promotions module in the admin control panel in MyBB (aka MyBulletinBoard)…
- CVE-2015-2786 — Critical (CVSS 10.0): Unspecified vulnerability in MyBB (aka MyBulletinBoard) before 1.8.4 has unknown attack vectors related to "Group join…
- CVE-2011-5133 — Critical (CVSS 10.0): Unspecified vulnerability in MyBB before 1.6.5 has unknown impact and attack vectors, related to an "unparsed user…
- CVE-2006-0218 — Critical (CVSS 10.0): Multiple unspecified vulnerabilities in MyBulletinBoard (MyBB) before 1.0.2 have unspecified impact and attack vectors,…
- CVE-2011-10018 — Critical (CVSS 9.8): myBB version 1.6.4 was distributed with an unauthorized backdoor embedded in the source code. The backdoor allowed…
- CVE-2020-22612 — Critical (CVSS 9.8): Installer RCE on settings file write in MyBB before 1.8.22.
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