How severe is CVE-2020-18661?

CVE-2020-18661 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-2020-18661 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-18661?

CVE-2020-18661 affects Sir Gnuboard. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-18661?

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

When was CVE-2020-18661 published?

CVE-2020-18661 was published on 2021-06-24 and last updated on 2026-06-17.

CVE-2020-18661

CVE-2020-18661 is a medium-severity vulnerability in Sir Gnuboard 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: 1% (63rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Sir Gnuboard
Published: 2021-06-24
Last modified: 2026-06-17

Description

Cross Site Scripting (XSS) vulnerability in gnuboard5 <=v5.3.2.8 via the url parameter to bbs/login.php.

Frequently asked questions

What is CVE-2020-18661?: Cross Site Scripting (XSS) vulnerability in gnuboard5 <=v5.3.2.8 via the url parameter to bbs/login.php.
How severe is CVE-2020-18661?: CVE-2020-18661 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-2020-18661 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (63rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-18661?: CVE-2020-18661 affects Sir Gnuboard. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-18661?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-18661 published?: CVE-2020-18661 was published on 2021-06-24 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:sir:gnuboard:*:*:*:*:*:*:*:*

More vulnerabilities in Sir Gnuboard

CVE-2020-18662 — Critical (CVSS 9.8): SQL Injection vulnerability in gnuboard5 <=v5.3.2.8 via the table_prefix parameter in install_db.php.
CVE-2005-0269 — Critical (CVSS 9.8): The file extension check in GNUBoard 3.40 and earlier only verifies extensions that contain all lowercase letters,…
CVE-2024-41475 — High (CVSS 8.8): Gnuboard g6 6.0.7 is vulnerable to Session hijacking due to a CORS misconfiguration.
CVE-2022-1252 — High (CVSS 8.2): Use of a Broken or Risky Cryptographic Algorithm in GitHub repository gnuboard/gnuboard5 prior to and including 5.5.5.…
CVE-2022-44216 — High (CVSS 7.5): Gnuboard 5.5.4 and 5.5.5 is vulnerable to Insecure Permissions. An attacker can change password of all users without…
CVE-2011-4066 — High (CVSS 7.5): SQL injection vulnerability in bbs/tb.php in Gnuboard 4.33.02 and earlier allows remote attackers to execute arbitrary…

All CVEs affecting Sir Gnuboard →

Other CWE-79 (Cross-site Scripting (XSS)) vulnerabilities

CVE-2025-49410 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Imran Emu TC…
CVE-2024-47875 — Critical (CVSS 10.0): DOMPurify is a DOM-only, super-fast, uber-tolerant XSS sanitizer for HTML, MathML and SVG. DOMpurify was vulnerable to…
CVE-2024-6886 — Critical (CVSS 10.0): Improper Neutralization of Input During Web Page Generation (XSS or 'Cross-site Scripting') vulnerability in Gitea…
CVE-2023-45144 — Critical (CVSS 10.0): com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on…
CVE-2023-45138 — Critical (CVSS 10.0): Change Request is an pplication allowing users to request changes on a wiki without publishing the changes directly.…
CVE-2022-4361 — Critical (CVSS 10.0): Keycloak, an open-source identity and access management solution, has a cross-site scripting (XSS) vulnerability in the…

Browse all CWE-79 (Cross-site Scripting (XSS)) vulnerabilities →