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HIGH severity

CVE-2026-40683 — keystone

HIGH

CVE-2026-40683 is a high-severity (CVSS 7.7) CWE-843 vulnerability in keystone. A fix is available for keystone — see the affected versions and patch details below.

OpenStack Keystone: LDAP identity backend does not convert enabled attribute to boolean

Also known asPYSEC-2026-2550
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 10, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-40683.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk
0.00%0.29%0.58%0.87%0.0%0.3%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍keystone

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIkeystoneall versions28.0.1pip install --upgrade 'keystone==28.0.1'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for keystone, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update keystone to 28.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-40683 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

There's a flaw in OpenStack Keystone's LDAP identity backend allows unauthorized access. When the `user_enabled_invert` configuration option is set to its default of `False`, users marked as disabled in LDAP are incorrectly treated as enabled within Keystone. This enables them to authenticate and perform actions,…

Workaround published by Red Hat
To mitigate this issue, configure OpenStack Keystone to correctly interpret the LDAP user enabled attribute. Set the `user_enabled_invert` option to `True` in the `keystone.conf` file. Example: ```ini [ldap] user_enabled_invert = True ``` After modifying the configuration, restart the Keystone service for the changes to take effect. This may temporarily disrupt authentication services. Additionally the user should start using an LDAP attribute with inverted semantics (such as nsAccountLock) to match the same semantics of the keystone side.
Source: Red Hat security advisory for CVE-2026-40683 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat OpenStack Services on OpenShift 18.0openstack-keystone-1:23.0.3-18.0.20260610133808.9e3dfb4.el9ostRHSA-2026:39808
UbuntuHIGH
USN-8433-1Ubuntu

Frequently Asked Questions

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
O3 Security · Impact-Aware SCA

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CVE-2026-40683: keystone — Fixed in 28.0.1