How severe is CVE-2021-27520?

CVE-2021-27520 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-27520 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27520?

CVE-2021-27520 affects Fudforum. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-27520?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-27520 published?

CVE-2021-27520 was published on 2021-03-19 and last updated on 2026-06-17.

CVE-2021-27520

CVE-2021-27520 is a medium-severity vulnerability in Fudforum with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Fudforum
Published: 2021-03-19
Last modified: 2026-06-17

Description

A cross-site scripting (XSS) issue in FUDForum 3.1.0 allows remote attackers to inject JavaScript via index.php in the "author" parameter.

Frequently asked questions

What is CVE-2021-27520?: A cross-site scripting (XSS) issue in FUDForum 3.1.0 allows remote attackers to inject JavaScript via index.php in the "author" parameter.
How severe is CVE-2021-27520?: CVE-2021-27520 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-27520 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27520?: CVE-2021-27520 affects Fudforum. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-27520?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-27520 published?: CVE-2021-27520 was published on 2021-03-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:fudforum:fudforum:3.1.0:*:*:*:*:*:*:*

More vulnerabilities in Fudforum

CVE-2019-18839 — Critical (CVSS 9.0): FUDForum 3.0.9 is vulnerable to Stored XSS via the nlogin parameter. This may result in remote code execution. An…
CVE-2019-18873 — Critical (CVSS 9.0): FUDForum 3.0.9 is vulnerable to Stored XSS via the User-Agent HTTP header. This may result in remote code execution. An…
CVE-2022-30860 — High (CVSS 7.2): FUDforum 3.1.2 is vulnerable to Remote Code Execution through Upload File feature of File Administration System in…
CVE-2013-2267 — High (CVSS 7.2): PHP Code Injection vulnerability in FUDforum Bulletin Board Software 3.0.4 could allow remote attackers to execute…
CVE-2024-30951 — Medium (CVSS 6.1): FUDforum v3.1.3 was discovered to contain a reflected cross-site scripting (XSS) vulnerability via the chpos parameter…
CVE-2021-27519 — Medium (CVSS 6.1): A cross-site scripting (XSS) issue in FUDForum 3.1.0 allows remote attackers to inject JavaScript via index.php in the…

All CVEs affecting Fudforum →

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