Apache James up to 3.9.0 SASL OAuthBearer XOAUTH2 improper authorization

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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9.5$5k-$25k0.00

Summaryinfo

A vulnerability identified as very critical has been detected in Apache James up to 3.9.0. This affects an unknown part of the component SASL OAuthBearer XOAUTH2. Performing a manipulation results in improper authorization. This vulnerability is known as CVE-2025-66621. Remote exploitation of the attack is possible. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Apache James up to 3.9.0. This affects some unknown functionality of the component SASL OAuthBearer XOAUTH2. The manipulation with an unknown input leads to a improper authorization vulnerability. CWE is classifying the issue as CWE-285. The product does not perform or incorrectly performs an authorization check when an actor attempts to access a resource or perform an action. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Apache James SASL OAuthBearer/XOAUTH2 prior versions 3.9.1 fails to validate correctly AUD claim of JWT payloads when introspection is not configured. This allows an attacker with valid credentials to access the mail server even if they are not authorized to do so. We recommend users to upgrade to non vulnerable version that forces explicit configuration of aud claims and forces introspection.

It is possible to read the advisory at lists.apache.org. This vulnerability is uniquely identified as CVE-2025-66621 since 12/05/2025. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 11/06/2026). The attack technique deployed by this issue is T1548.002 according to MITRE ATT&CK.

Upgrading to version 3.9.1 eliminates this vulnerability.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper authorization
CWE: CWE-285 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: James 3.9.1

Timelineinfo

12/05/2025 CVE reserved
11/06/2026 +336 days Advisory disclosed
11/06/2026 +0 days VulDB entry created
11/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: apache.org

Advisory: lists.apache.org
Status: Confirmed

CNA: apache
CVE: CVE-2025-66621 (🔒)

GCVE (CVE): GCVE-0-2025-66621
GCVE (VulDB): GCVE-100-431895

Entryinfo

Created: 11/06/2026 13:08
Changes: 11/06/2026 13:08 (54)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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