How severe is CVE-2026-8337?

CVE-2026-8337 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2026-8337 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-8337?

CVE-2026-8337 affects Concretecms Concrete Cms. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-8337?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-8337 have an EU (EUVD) identifier?

Yes. CVE-2026-8337 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31359.

When was CVE-2026-8337 published?

CVE-2026-8337 was published on 2026-05-21 and last updated on 2026-06-17.

CVE-2026-8337

CVE-2026-8337 is a medium-severity vulnerability in Concretecms Concrete Cms with a CVSS 3.x base score of 5.3. 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-565.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 6.3
EPSS exploit prediction: 0% (9th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-31359
Weakness: CWE-565
Affected product: Concretecms Concrete Cms
Published: 2026-05-21
Last modified: 2026-06-17

Description

Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey’s endpoint. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Zer0daySec https://github.com/Zee99y for reporting

Frequently asked questions

What is CVE-2026-8337?: Concrete CMS 9.5.0 and below is vulnerable to IDOR in surveys. To be vulnerable, a site would have to be configured in such a way that both public and private surveys are present on the site. An unauthenticated attacker can vote in the restricted survey by submitting the restricted optionID through the public survey’s endpoint. The Concrete CMS security team gave this vulnerability a CVSS v.4.0 score of 6.3 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Zer0daySec https://github.com/Zee99y for reporting
How severe is CVE-2026-8337?: CVE-2026-8337 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2026-8337 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (9th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-8337?: CVE-2026-8337 affects Concretecms Concrete Cms. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-8337?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-8337 have an EU (EUVD) identifier?: Yes. CVE-2026-8337 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31359.
When was CVE-2026-8337 published?: CVE-2026-8337 was published on 2026-05-21 and last updated on 2026-06-17.

References

https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes

Affected products (1)

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

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