CVE-2026-40205: open-xchange gmbh ox dovecot ce Improper Authentication
Vulnerability summary
CVE-2026-40205 is a medium (CVSS 5.9) Improper Authentication vulnerability in open-xchange gmbh ox dovecot ce. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 10.7% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 5 · Related 4Timeline
- 28-08-2026PublishedVulnerability first disclosed.
- 28-08-2026Last modifiedVulnerability information updated.
Description
An attacker that holds an OAuth2 token granting only part of the required scopes can authenticate, because when more than one scope is required in the configuration, the remote token validation paths accept a token that carries only one of them, while the local token validation path correctly requires all of them. The configured authorization policy is not enforced, so a token that was granted only part of the required permissions is accepted where it should have been rejected. Use local token validation where tokens can be validated locally. Update to non-vulnerable version. No publicly available exploits are known.
CVSS metrics
5 scores · 5 sources · 1 version- OSV · AlpineEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
- OSV · DebianEcosystem advisory · calculated5.9MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
- NVDNIST5.9MediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:H/A:N
EPSS trend
Probability
0.21%
Chance of exploitation in the next 30 days
Percentile
11%
Versus all other CVEs
30-day change
+0.03 pp
From 0.18% on 21-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Open-xchange gmbh2 products
- ox dovecot ce≥ 2.3.11.2, < 2.4.5
- ox dovecot pro≥ 2.3.11.2, < 2.3.22.2 | ≥ 3.0.0, < 3.0.7 | ≥ 3.1.0, < 3.1.6
Alpine1 product
- dovecot< 2.4.5-r0
Debian1 product
- dovecotAll versions (No fix recorded) | < 1:2.4.1+dfsg1-6+deb13u7 | < 1:2.4.5+dfsg1-1
Ubuntu1 product
- dovecotAll versions (No fix recorded)
4 vendors · 5 products
