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Vulnerability record · CVE-2021-22958 · published 7 October 2021

CVE-2021-22958: Concretecms concrete cms server-side request forgery (ssrf) vulnerability

Concretecms · Concrete Cms

A Server-Side Request Forgery vulnerability was found in concrete5 < 8.5.5 that allowed a decimal notation encoded IP address to bypass the limitations in place for localhost allowing interaction with local services. Impact can vary depending on services exposed.CVSSv2.0 AV:A/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N

9.8 CVSS 3.1 Critical EPSS 1.2% · top 32.4% CWE-918 · Server-side request forgery (SSRF)
9.8CVSS 3.1 base score, v2 7.5
1.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

Description

A Server-Side Request Forgery vulnerability was found in concrete5 < 8.5.5 that allowed a decimal notation encoded IP address to bypass the limitations in place for localhost allowing interaction with local services. Impact can vary depending on services exposed.CVSSv2.0 AV:A/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:N

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://documentation.concretecms.org/developers/introduction/version-history/855-release-notes Release NotesVendor Advisory
https://hackerone.com/reports/863221 Issue TrackingPermissions RequiredThird Party Advisory
https://documentation.concretecms.org/developers/introduction/version-history/855-release-notes Release NotesVendor Advisory
https://hackerone.com/reports/863221 Issue TrackingPermissions RequiredThird Party Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-22958), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.