How severe is CVE-2026-8661?

CVE-2026-8661 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2026-8661 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-8661?

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

Does CVE-2026-8661 have an EU (EUVD) identifier?

Yes. CVE-2026-8661 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39616.

When was CVE-2026-8661 published?

CVE-2026-8661 was published on 2026-06-26.

CVE-2026-8661

CVE-2026-8661 is a medium-severity vulnerability with a CVSS 3.x base score of 4.8. 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 4.8)
EPSS exploit prediction: 0% (17th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-39616
Weakness: CWE-79
Published: 2026-06-26
Last modified: 2026-06-26

Description

Server-Side Cross-Site Scripting and Server-Side Request Forgery vulnerability in the markdown_to_pdf action of Rapid7 InsightConnect Markdown Plugin version 3.1.4 and earlier on Linux allows remote attackers to execute JavaScript server-side and make arbitrary outbound HTTP requests via crafted content embedded in Markdown input. The PDF rendering engine does not restrict script execution or outbound network access.

Frequently asked questions

What is CVE-2026-8661?: Server-Side Cross-Site Scripting and Server-Side Request Forgery vulnerability in the markdown_to_pdf action of Rapid7 InsightConnect Markdown Plugin version 3.1.4 and earlier on Linux allows remote attackers to execute JavaScript server-side and make arbitrary outbound HTTP requests via crafted content embedded in Markdown input. The PDF rendering engine does not restrict script execution or outbound network access.
How severe is CVE-2026-8661?: CVE-2026-8661 has a CVSS 3.x base score of 4.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-8661 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (17th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-8661?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-8661 have an EU (EUVD) identifier?: Yes. CVE-2026-8661 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-39616.
When was CVE-2026-8661 published?: CVE-2026-8661 was published on 2026-06-26.

References

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…
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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…

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