How severe is CVE-2020-26286?

CVE-2020-26286 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2020-26286 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26286?

CVE-2020-26286 affects Hedgedoc. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-26286?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-26286 published?

CVE-2020-26286 was published on 2020-12-29 and last updated on 2026-06-17.

CVE-2020-26286

CVE-2020-26286 is a high-severity vulnerability in Hedgedoc with a CVSS 3.x base score of 7.5. 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-434.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 1% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-434
Affected product: Hedgedoc
Published: 2020-12-29
Last modified: 2026-06-17

Description

HedgeDoc is a collaborative platform for writing and sharing markdown. In HedgeDoc before version 1.7.1 an unauthenticated attacker can upload arbitrary files to the upload storage backend including HTML, JS and PHP files. The problem is patched in HedgeDoc 1.7.1. You should however verify that your uploaded file storage only contains files that are allowed, as uploaded files might still be served. As workaround it's possible to block the `/uploadimage` endpoint on your instance using your reverse proxy. And/or restrict MIME-types and file names served from your upload file storage.

Frequently asked questions

What is CVE-2020-26286?: HedgeDoc is a collaborative platform for writing and sharing markdown. In HedgeDoc before version 1.7.1 an unauthenticated attacker can upload arbitrary files to the upload storage backend including HTML, JS and PHP files. The problem is patched in HedgeDoc 1.7.1. You should however verify that your uploaded file storage only contains files that are allowed, as uploaded files might still be served. As workaround it's possible to block the `/uploadimage` endpoint on your instance using your reverse proxy. And/or restrict MIME-types and file names served from your upload file storage.
How severe is CVE-2020-26286?: CVE-2020-26286 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2020-26286 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26286?: CVE-2020-26286 affects Hedgedoc. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-26286?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-26286 published?: CVE-2020-26286 was published on 2020-12-29 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:hedgedoc:hedgedoc:*:*:*:*:*:*:*:*

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Other CWE-434 (Unrestricted Upload of File with Dangerous Type) vulnerabilities

CVE-2026-39770 — Critical (CVSS 10.0): Unauthenticated Arbitrary File Upload in Doctreat <= 1.7.0 versions.
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CVE-2026-84147 — Critical (CVSS 10.0): This vulnerability exists in the ERP system due to improper authentication controls and inadequate file type validation…
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