CVE-2026-42999: An issue was discovered in OpenStack Keystone before 29.0.2

Routine

MEDIUM 6.0UPGRADE

CVE-2026-42999 is a medium-severity flaw (CVSS 6.0) affecting keystone. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in OpenStack Keystone before 29.0.2. The Keystone RBAC policy enforcer in enforce_call unconditionally merges the raw JSON request body into the policy enforcement dictionary via policy_dict.update(json_input.copy()), overwriting trusted target data that was previously set from database lookups. Because flask.request.get_json is called with force=True, this works regardless of Content-Type or HTTP method. Any authenticated

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.0 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-863, CWE-639
Published	2026-05-28
Last modified	2026-10-26

Publisher (CNA): MITRE · Vendor: openstack

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-28 19:16 UTCPublished CVE record published
2026-10-26 13:10 UTCUpdated Record last modified

openstack keystone UPGRADE

Affected: >= 14.0.0 and < 27.0.2 · >= 28.0.0 and < 28.0.2 · >= 29.0.0 and < 29.0.2

Fixed in: 27.0.2, 28.0.2, 29.0.2

Safe to downgrade to: a release before 14.0.0

1. Check installed version

apt-cache policy keystone || rpm -q keystone || keystone --version

2. UPGRADE to 27.0.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade keystone

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade keystone

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 14.0.0 (Debian / Ubuntu)

apt-cache madison keystone sudo apt install keystone=<VERSION_BEFORE_14.0.0> sudo apt-mark hold keystone

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list keystone sudo dnf downgrade keystone-<VERSION_BEFORE_14.0.0> sudo dnf versionlock add keystone

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-42999?

keystone: upgrade to 27.0.2, 28.0.2, 29.0.2. Exact commands for each OS are on this page.

Is CVE-2026-42999 being exploited?

CVE-2026-42999 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-42999 affect?

CVE-2026-42999 affects keystone. Severity is medium (CVSS 6.0). An issue was discovered in OpenStack Keystone before 29.0.2. The Keystone RBAC policy enforcer in enforce_call unconditionally merges the raw JSON request body into the policy enforcement dictionary via policy_dict.update(json_input.copy())

How urgent is CVE-2026-42999?

Priority 32/100. Public exploit reference

Software pages

OpenStack vulnerabilities · Flask vulnerabilities

Related CVEs

CVE-2026-33551 LOW 3.5 UPGRADE An issue was discovered in OpenStack Keystone 14 through 26 before 26.1.1, 27.0.0, 28.0.0, and 29.0.0
CVE-2026-43001 HIGH 7.9 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-42998 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-43000 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-44394 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2

References

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