HOMEVULNERABILITIESCVE-2021-22958
CRITICAL

CVE-2021-22958

CWE-918Published: October 7, 2021· Updated: Jun 17, 2026

9.8
CVSS v3.1

Official 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

NVD Source

Technical Analysis

CVE-2021-22958 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected Vendors & Products

concretecms1 product(s)
concrete cms
Source: NVD CPE · 1 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://documentation.concretecms.org/developers/introduction/version-history/855-release-notes
ADVISORYhttps://hackerone.com/reports/863221
ADVISORYhttps://documentation.concretecms.org/developers/introduction/version-history/855-release-notes
ADVISORYhttps://hackerone.com/reports/863221

All References (4)

→
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

Quick Facts

CVE IDCVE-2021-22958
CVSS Score9.8 / 10
SeverityCRITICAL
WeaknessCWE-918
CISA KEVNo
Affected1 vendor(s)
PublishedOct 7, 2021

Related CVEs (CWE-918)

CVE-2026-2053
10.0
CVE-2026-47938
10.0
CVE-2026-28798
10.0
CVE-2026-35431
10.0
CVE-2023-3432
10.0
CVE-2026-13773
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-22958 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
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