CVE-2021-22958

Name: CVE-2021-22958
Creator: NVD / NIST
Published: 2021-10-07T14:15:08.107+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 1.19%

Last modified Jun 17, 2026

CVE-2021-22958 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 1.19% chance of exploitation in the next 30 days.

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

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

1.19%

63.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Concretecms	Concrete Cms	< 8.5.5

References

https://documentation.concretecms.org/developers/introduction/version-history/855-release-notesRelease Notes, Vendor Advisory
https://hackerone.com/reports/863221Issue Tracking, Permissions Required, Third Party Advisory
https://documentation.concretecms.org/developers/introduction/version-history/855-release-notesRelease Notes, Vendor Advisory
https://hackerone.com/reports/863221Issue Tracking, Permissions Required, Third Party Advisory

Timeline

Published: Oct 7, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-22958?

How severe is CVE-2021-22958?

CVE-2021-22958 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 1.19% probability of exploitation in the next 30 days.

How do I fix CVE-2021-22958?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-22958?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST