How severe is CVE-2021-3758?

CVE-2021-3758 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2021-3758 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-3758?

CVE-2021-3758 affects Bookstackapp Bookstack. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-3758?

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

When was CVE-2021-3758 published?

CVE-2021-3758 was published on 2021-09-02 and last updated on 2026-06-17.

CVE-2021-3758

CVE-2021-3758 is a medium-severity vulnerability in Bookstackapp Bookstack with a CVSS 3.x base score of 6.5. 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-918.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.0
EPSS exploit prediction: 1% (52nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-918
Affected product: Bookstackapp Bookstack
Published: 2021-09-02
Last modified: 2026-06-17

Description

bookstack is vulnerable to Server-Side Request Forgery (SSRF)

Frequently asked questions

What is CVE-2021-3758?: bookstack is vulnerable to Server-Side Request Forgery (SSRF)
How severe is CVE-2021-3758?: CVE-2021-3758 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2021-3758 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (52nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-3758?: CVE-2021-3758 affects Bookstackapp Bookstack. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-3758?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-3758 published?: CVE-2021-3758 was published on 2021-09-02 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:bookstackapp:bookstack:*:*:*:*:*:*:*:*

More vulnerabilities in Bookstackapp Bookstack

CVE-2021-4119 — Critical (CVSS 9.8): bookstack is vulnerable to Improper Access Control
CVE-2020-5256 — High (CVSS 7.9): BookStack before version 0.25.5 has a vulnerability where a user could upload PHP files through image upload functions,…
CVE-2020-26211 — High (CVSS 7.7): In BookStack before version 0.30.4, a user with permissions to edit a page could insert JavaScript code through the use…
CVE-2020-26210 — High (CVSS 7.7): In BookStack before version 0.30.4, a user with permissions to edit a page could add an attached link which would…
CVE-2021-3944 — Medium (CVSS 6.8): bookstack is vulnerable to Cross-Site Request Forgery (CSRF)
CVE-2023-6199 — Medium (CVSS 6.5): Book Stack version 23.10.2 allows filtering local files on the server. This is possible because the application is…

All CVEs affecting Bookstackapp Bookstack →

Other CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities

CVE-2026-47938 — Critical (CVSS 10.0): Adobe Campaign Classic (ACC) versions 7.4.3 build 9394 and earlier are affected by a Server-Side Request Forgery (SSRF)…
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CVE-2026-32186 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Microsoft Bing allows an unauthorized attacker to elevate privileges over a…
CVE-2026-33107 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Azure Databricks allows an unauthorized attacker to elevate privileges over a…
CVE-2026-32871 — Critical (CVSS 10.0): FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP…
CVE-2026-32169 — Critical (CVSS 10.0): Server-side request forgery (ssrf) in Azure Cloud Shell allows an unauthorized attacker to elevate privileges over a…

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