How severe is CVE-2026-18423?

CVE-2026-18423 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2026-18423 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-18423?

CVE-2026-18423 affects Concretecms Concrete Cms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-18423?

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-2026-18423 published?

CVE-2026-18423 was published on 2026-09-15 and last updated on 2026-09-21.

CVE-2026-18423

CVE-2026-18423 is a high-severity vulnerability in Concretecms Concrete Cms with a CVSS 3.x base score of 7.1. 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-639.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v4: 2.1
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-639
Affected product: Concretecms Concrete Cms
Published: 2026-09-15
Last modified: 2026-09-21

Description

Concrete CMS 9.0.0 through 9.5.2 is vulnerable to Insecure direct object reference (IDOR) in the Express saved search preset delete and edit dialogs . An authenticated user holding only view permission on a single Express entity could therefore permanently delete, with no undo, or rename saved search presets owned by Express entities for which they had no permission, and a renamed preset name was displayed back to users of the targeted entity, enabling defacement or social engineering. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Yalguun Tumenkhuu ( fg0x0 ) for reporting.

Frequently asked questions

What is CVE-2026-18423?: Concrete CMS 9.0.0 through 9.5.2 is vulnerable to Insecure direct object reference (IDOR) in the Express saved search preset delete and edit dialogs . An authenticated user holding only view permission on a single Express entity could therefore permanently delete, with no undo, or rename saved search presets owned by Express entities for which they had no permission, and a renamed preset name was displayed back to users of the targeted entity, enabling defacement or social engineering. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.1 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N. Thanks Yalguun Tumenkhuu ( fg0x0 ) for reporting.
How severe is CVE-2026-18423?: CVE-2026-18423 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2026-18423 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-18423?: CVE-2026-18423 affects Concretecms Concrete Cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-18423?: 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-2026-18423 published?: CVE-2026-18423 was published on 2026-09-15 and last updated on 2026-09-21.

References

https://documentation.concretecms.org/developers/introduction/version-history/953-release-notes

Affected products (1)

cpe:2.3:a:concretecms:concrete_cms:*:*:*:*:*:*:*:*

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