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🛡️ CVE-2026-8337 — concrete-cms

🟡 CVSS 5.3 — Medium ✅ No Known Exploit CWE-565 NVD
5.3
CVSS Score
0 Low4 Medium7 High9 Critical10

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

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-8337 is classified as CWE-565: Reliance on Cookies without Validation. Security decisions are based on cookie values that the client can freely modify.

Affected software

CVE-2026-8337 is recorded against 2 packages.

  • concrete-cms (fixed in 9.5.1)
  • concrete5/concrete5 (fixed in 9.5.1)

Timeline and source

Published on 21 May 2026 and last revised on 23 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

documentation.concretecms.org

Other advisories for this package

concrete-cms has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-565: Reliance on Cookies without Validation) in other software:

Details

Severity MEDIUM
CVSS Score 5.3
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE CWE-565
Public Exploit ✅ No
Source NVD
Published 2026-05-21
Updated 2026-08-20
Modified 2026-07-23
Fix URL N/A

Affected Packages

Software From version Fixed in
concrete-cms — 9.5.1
concrete5/concrete5 — 9.5.1

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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