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CVE-2026-85387

LOW 2 ALL-YEARS

Published 2026-09-16 · Last modified 2026-09-17 · ConcreteCMS · NVD: Analyzed

Concrete CMS before 9.5.4 re-authorized OAuth REST API requests from the bearer token alone and did not re-check the state of the account the token had been issued to. The resource server's authorization validator confirmed only that a token existed, had not expired, and had not been explicitly revoked, and deactivating a user did not revoke that user's outstanding tokens. As a result, a deactivated user retained full access to /ccm/api/1.0/* for the remaining lifetime of any token already issued to them. The same gap applied to accounts that had been deleted or locked pending a forced password reset. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 2.0 with vector CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N. Thanks Myq Larson for reporting.

LIMITED SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.3%chance of exploitation in 30 days · 17th percentile

○ In CISA KEV○ Public exploit / PoC◆ SSVC: exploitation none, automatable no

Impact if exploited

2CVSS 4.0 · LOW · CNA

  • ConfidentialityLow
  • IntegrityLow
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ⚠User interaction: Requires active user interaction
  • ⚠Complexity: Needs a race window or specific setup
  • ⚠Requirements: Specific conditions must be present

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.

Affected

Vendors Concrete Cms Concretecms

Products Concrete Cms

Weakness (CWE)

  • CWE-613: Insufficient Session Expiration

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Known Affected Software Configurations

VendorProductVersion range
ConcretecmsConcrete Cms< 9.5.4

All CVSS metrics

  • LOW 2 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
  • LOW 2 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
  • HIGH 7.1 v3.1 · NVD Primary
    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N

References

Patches & mitigations

Sources: NVD · CVE.org · EPSS