CVE-2025-48877
CVE-2025-48877 is a critical-severity vulnerability in Discourse with a CVSS 3.x base score of 9.8. 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-1038.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v4: 8.1
- EPSS exploit prediction: 0% (27th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2025-17469
- Weakness: CWE-1038
- Affected product: Discourse
- Published:
- Last modified:
Description
Discourse is an open-source discussion platform. Prior to version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch, Codepen is present in the default `allowed_iframes` site setting, and it can potentially auto-run arbitrary JS in the iframe scope, which is unintended. This issue is patched in version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch. As a workaround, the Codepen prefix can be removed from a site's `allowed_iframes`.
Frequently asked questions
- What is CVE-2025-48877?
- Discourse is an open-source discussion platform. Prior to version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch, Codepen is present in the default `allowed_iframes` site setting, and it can potentially auto-run arbitrary JS in the iframe scope, which is unintended. This issue is patched in version 3.4.4 of the `stable` branch, version 3.5.0.beta5 of the `beta` branch, and version 3.5.0.beta6-dev of the `tests-passed` branch. As a workaround, the Codepen prefix can be removed from a site's `allowed_iframes`.
- How severe is CVE-2025-48877?
- CVE-2025-48877 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2025-48877 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2025-48877?
- CVE-2025-48877 primarily affects Discourse. In total, 6 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2025-48877?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2025-48877 have an EU (EUVD) identifier?
- Yes. CVE-2025-48877 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-17469.
- When was CVE-2025-48877 published?
- CVE-2025-48877 was published on 2025-06-09 and last updated on 2026-06-17.
References
Affected products (6)
- cpe:2.3:a:discourse:discourse:*:*:*:*:stable:*:*:*
- cpe:2.3:a:discourse:discourse:*:*:*:*:beta:*:*:*
- cpe:2.3:a:discourse:discourse:3.5.0:beta1:*:*:beta:*:*:*
- cpe:2.3:a:discourse:discourse:3.5.0:beta2:*:*:beta:*:*:*
- cpe:2.3:a:discourse:discourse:3.5.0:beta3:*:*:beta:*:*:*
- cpe:2.3:a:discourse:discourse:3.5.0:beta4:*:*:beta:*:*:*
More vulnerabilities in Discourse
- CVE-2021-41163 — Critical (CVSS 10.0): Discourse is an open source platform for community discussion. In affected versions maliciously crafted requests could…
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- 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…
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- 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)…
- CVE-2023-48297 — High (CVSS 8.6): Discourse is a platform for community discussion. The message serializer uses the full list of expanded chat mentions…
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