How severe is CVE-2026-40683?

CVE-2026-40683 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.

Is CVE-2026-40683 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-40683?

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.

Does CVE-2026-40683 have an EU (EUVD) identifier?

Yes. CVE-2026-40683 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22701.

When was CVE-2026-40683 published?

CVE-2026-40683 was published on 2026-04-14 and last updated on 2026-06-17.

CVE-2026-40683

CVE-2026-40683 is a high-severity vulnerability with a CVSS 3.x base score of 7.7. 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-843.

Key facts

Severity: High (CVSS 3.x base score 7.7)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-22701
Weakness: CWE-843
Published: 2026-04-14
Last modified: 2026-06-17

Description

In OpenStack Keystone before 28.0.1, the LDAP identity backend does not convert the user enabled attribute to a boolean when the user_enabled_invert configuration option is False (the default). The _ldap_res_to_model method in the UserApi class only performed string-to-boolean conversion when user_enabled_invert was True. When False, the raw string value from LDAP (e.g., "FALSE") was used directly. Since non-empty strings are truthy in Python, users marked as disabled in LDAP were treated as enabled by Keystone, allowing them to authenticate and perform actions. All deployments using the LDAP identity backend without user_enabled_invert=True or user_enabled_emulation are affected.

Frequently asked questions

What is CVE-2026-40683?: In OpenStack Keystone before 28.0.1, the LDAP identity backend does not convert the user enabled attribute to a boolean when the user_enabled_invert configuration option is False (the default). The _ldap_res_to_model method in the UserApi class only performed string-to-boolean conversion when user_enabled_invert was True. When False, the raw string value from LDAP (e.g., "FALSE") was used directly. Since non-empty strings are truthy in Python, users marked as disabled in LDAP were treated as enabled by Keystone, allowing them to authenticate and perform actions. All deployments using the LDAP identity backend without user_enabled_invert=True or user_enabled_emulation are affected.
How severe is CVE-2026-40683?: CVE-2026-40683 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability high.
Is CVE-2026-40683 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-40683?: 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.
Does CVE-2026-40683 have an EU (EUVD) identifier?: Yes. CVE-2026-40683 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-22701.
When was CVE-2026-40683 published?: CVE-2026-40683 was published on 2026-04-14 and last updated on 2026-06-17.

References

Other CWE-843 vulnerabilities

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CVE-2023-22579 — Critical (CVSS 9.9): Due to improper parameter filtering in the sequalize js library, can a attacker peform injection.
CVE-2026-13776 — Critical (CVSS 9.8): Type Confusion in Dawn in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2026-43038 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in…
CVE-2025-70023 — Critical (CVSS 9.8): An issue pertaining to CWE-843: Access of Resource Using Incompatible Type was discovered in transloadit uppy v0.25.6.

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