CVE-2026-81916

CVE-2026-81916 is a medium-severity vulnerability in Concretecms Concrete Cms with a CVSS 3.x base score of 4.3. 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

Description

Concrete CMS before 9.5.3 evaluated the authorization check for an Express entry submission against the entity of the posted form rather than the entity identified by the dashboard route. As a result, a user permitted to add entries to one Express object could create entries in a different Express object outside their authorization scope, potentially polluting protected datasets, triggering workflows, or injecting content into administrative processes. The dashboard submit route resolved the mutated entity from the attacker-controlled route ID while the permission check validated the independently posted form's entity, and the submission proceeded because the two entities were never compared. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Frequently asked questions

What is CVE-2026-81916?
Concrete CMS before 9.5.3 evaluated the authorization check for an Express entry submission against the entity of the posted form rather than the entity identified by the dashboard route. As a result, a user permitted to add entries to one Express object could create entries in a different Express object outside their authorization scope, potentially polluting protected datasets, triggering workflows, or injecting content into administrative processes. The dashboard submit route resolved the mutated entity from the attacker-controlled route ID while the permission check validated the independently posted form's entity, and the submission proceeded because the two entities were never compared. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 5.1 with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.
How severe is CVE-2026-81916?
CVE-2026-81916 has a CVSS 3.x base score of 4.3, 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 low, and availability none.
Is CVE-2026-81916 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-81916?
CVE-2026-81916 affects Concretecms Concrete Cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-81916?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-81916 published?
CVE-2026-81916 was published on 2026-09-11 and last updated on 2026-09-18.

References

Affected products (1)

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