CVE-2025-66488
CVE-2025-66488 is a medium-severity vulnerability in Discourse with a CVSS 3.x base score of 4.6. 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-116.
Key facts
- Severity: Medium (CVSS 3.x base score 4.6)
- EPSS exploit prediction: 0% (7th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-206449
- Weakness: CWE-116
- Affected product: Discourse
- Published:
- Last modified:
Description
Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider deleting them.
Frequently asked questions
- What is CVE-2025-66488?
- Discourse is an open source discussion platform. A vulnerability present in versions prior to 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 affects anyone who uses S3 for uploads. While scripts may be executed, they will only be run in the context of the S3/CDN domain, with no site credentials. Versions 3.5.4, 2025.11.2, 2025.12.1, and 2026.1.0 fix the issue. As a workaround, disallow html or xml files for uploads in authorized_extensions. For existing html xml uploads, site owners can consider deleting them.
- How severe is CVE-2025-66488?
- CVE-2025-66488 has a CVSS 3.x base score of 4.6, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is none, integrity low, and availability low.
- Is CVE-2025-66488 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (7th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-66488?
- CVE-2025-66488 primarily affects Discourse. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2025-66488?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- Does CVE-2025-66488 have an EU (EUVD) identifier?
- Yes. CVE-2025-66488 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-206449.
- When was CVE-2025-66488 published?
- CVE-2025-66488 was published on 2026-01-28 and last updated on 2026-06-17.
References
Affected products (3)
- cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:*
- cpe:2.3:a:discourse:discourse:2025.12.0:*:*:*:stable:*:*:*
- cpe:2.3:a:discourse:discourse:2026.1.0:*:*:*:stable:*:*:*
More vulnerabilities in Discourse
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- CVE-2025-48877 — Critical (CVSS 9.8): Discourse is an open-source discussion platform. Prior to version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of…
- CVE-2022-36066 — Critical (CVSS 9.1): Discourse is an open source discussion platform. In versions prior to 2.8.9 on the `stable` branch and prior to…
- CVE-2022-39356 — High (CVSS 8.9): Discourse is a platform for community discussion. Users who receive an invitation link that is not scoped to a single…
- CVE-2023-22468 — High (CVSS 8.8): Discourse is an open source platform for community discussion. Versions prior to 2.8.13 (stable), 3.0.0.beta16 (beta)…
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