CVE-2021-27889

Exploitation

Not assessed. CISA has not published an exploitation assessment for this record, and it is not in the KEV catalog. That is an absence of assessment, not a finding of no risk.

SSVC decision

Not assessed by CISA

EPSS probability

5.07% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 91.6% of scored records. A rank, not a probability.

NVD base score

6.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-03-15 16:57Z5 YR AGO

Last updated

2024-08-03 21:33Z2 YR AGO

Reserved

2021-03-02

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Not rated by the issuing CNA

CNA CVSS vector

Not published by the issuing CNA

Weaknesses

• CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')Base

Data version

5.1

Document digest

952c3281de33ac0b6ddf76f8a6242138e1165c8c808a8cc48b94acad71a1dbd6

• github.comhttps://github.com/mybb/mybb/security/advisories/GHSA-xhj7-3349-mqcmx_refsource_MISC
• packetstormsecurity.comhttp://packetstormsecurity.com/files/161908/MyBB-1.8.25-Remote-Command-Execution.htmlx_refsource_MISC
• blog.sonarsource.comhttps://blog.sonarsource.com/mybb-remote-code-execution-chainx_refsource_MISC