Ubuntu update for keystone

1) Incorrect authorization

EUVDB-ID: #VU118095

Risk: Critical

CVSSv4.0: 8.1 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:U/U:Red]

CVE-ID: N/A

CWE-ID: CWE-863 - Incorrect Authorization

Exploit availability: No

Description

The vulnerability allows a remote attacker to gain access to sensitive information.

The vulnerability exists due to incorrect authorization checks within the ec2tokens and s3tokens API endpoints. A remote non-authenticated attacker can send a valid AWS Signature (e.g., from a presigned S3 URL) and obtain Keystone authorization (ec2tokens can yield a fully scoped token; s3tokens can reveal scope accepted by some services), resulting in unauthorized access and code execution.

Deployments where /v3/ec2tokens or /v3/s3tokens are reachable by unauthenticated clients (e.g., exposed on a public API) are affected.

Mitigation

Update the affected package keystone to the latest version.

Vulnerable software versions

Ubuntu: 24.04 - 25.10

keystone (Ubuntu package): before 2:25.0.0-0ubuntu1.1

CPE2.3

• cpe:2.3:o:canonical:ubuntu:24.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu:25.04:*:*:*:*:*:*:*
• cpe:2.3:o:canonical:ubuntu:25.10:*:*:*:*:*:*:*
• cpe:2.3:a:canonical:keystone_ubuntu_package:*:*:*:*:*:ubuntu:*:*

External links

https://ubuntu.com/security/notices/USN-7857-1

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.