CVE-2025-66621: Apache James SASL OAuthBearer/XOAUTH2 prior versions 3.9.1 fails to validate correctly AUD claim of JWT payloa

Routine

HIGH n/aWATCHLISTUPGRADE

CVE-2025-66621 is a high-severity flaw (CVSS n/a) affecting apache james. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	n/a (High)
EPSS exploit chance	n/a
CISA exploited list	No
Weakness	CWE-345
Published	2026-11-06
Last modified	2026-11-06

Publisher (CNA): apache · Vendor: apache software foundation · Source: CVE Program record (NVD analysis pending)

Last updated 2026-11-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-11-06 11:38 UTCPublished CVE record published
2026-11-06 11:38 UTCUpdated Record last modified

apache software foundation apache james UPGRADE

Affected: >= 3.9.0 and < 3.9.1

Fixed in: 3.9.1

Safe to downgrade to: a release before 3.9.0

1. Check installed version

apt-cache policy apache-james || rpm -q apache-james || apache-james --version

2. UPGRADE to 3.9.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade apache-james

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade apache-james

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 3.9.0 (Debian / Ubuntu)

apt-cache madison apache-james sudo apt install apache-james=<VERSION_BEFORE_3.9.0> sudo apt-mark hold apache-james

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

dnf --showduplicates list apache-james sudo dnf downgrade apache-james-<VERSION_BEFORE_3.9.0> sudo dnf versionlock add apache-james

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-2025-66621?

apache james: upgrade to 3.9.1. Exact commands for each OS are on this page.

Is CVE-2025-66621 being exploited?

CVE-2025-66621 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-2025-66621 affect?

CVE-2025-66621 affects apache james. Severity is high (CVSS n/a). 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 ar

How urgent is CVE-2025-66621?

Priority 5/100. On your watchlist

Related CVEs

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CVE-2026-49939 HIGH n/a UPGRADE In Apache James server prior version 3.9.1 improper Access Control List processing is exposed by the JMAP prot

References

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