CVE-2021-27889 EXPLOIT
6.1
MEDIUM · CVSS 3.1 · EPSS 5.1% (pctl 92)
Patch early
A public exploit exists.
Description
Cross-site Scripting (XSS) vulnerability in MyBB before 1.8.26 via Nested Auto URL when parsing messages.
Scoring
| CVSS | 6.1 (MEDIUM, v3.1) |
|---|---|
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| EPSS | 5.07% — more likely to be exploited than 92% of all CVEs |
| Weakness | CWE-79 |
| On CISA KEV | no |
| Public exploit | yes |
| Published | 2021-03-15 |
| Last modified | 2026-06-17 |
Affected (1)
| Vendor | Product |
|---|---|
| mybb | mybb |
Public exploits
| Source | Title | Date |
|---|---|---|
| exploit-db | MyBB 1.8.25 - Chained Remote Command Execution | 2021-03-22 |
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-xhj7-3349-mqcm
- 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-xhj7-3349-mqcm
→ the Explorer · watch your stack · NVD