CVE-2025-53379: A out-of-bounds read vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.2, FortiAuthenticator 6.5

This month

HIGH 7.5REMOTEUPGRADE

CVE-2025-53379 is a high-severity flaw (CVSS 7.5) affecting fortiauthenticator. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A out-of-bounds read vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.2, FortiAuthenticator 6.5 all versions may allow a remote unauthenticated attacker to retrieve sensitive information via a specially crafted request.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-125
Published	2026-07-14
Last modified	2026-09-29

Publisher (CNA): Fortinet, Inc. · Vendor: fortinet

Last updated 2026-09-29 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-14 16:16 UTCPublished CVE record published
2026-09-29 19:10 UTCUpdated Record last modified

fortinet fortiauthenticator UPGRADE

Affected: >= 6.5.0 and <= 6.5.7 · >= 6.6.0 and <= 6.6.2

Fixed in: newer than 6.6.2

Safe to downgrade to: a release before 6.5.0

1. Check installed version

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

2. UPGRADE to newer than 6.6.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade fortiauthenticator

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 6.5.0 (Debian / Ubuntu)

apt-cache madison fortiauthenticator sudo apt install fortiauthenticator=<VERSION_BEFORE_6.5.0> sudo apt-mark hold fortiauthenticator

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

dnf --showduplicates list fortiauthenticator sudo dnf downgrade fortiauthenticator-<VERSION_BEFORE_6.5.0> sudo dnf versionlock add fortiauthenticator

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-2025-53379?

fortiauthenticator: upgrade to newer than 6.6.2. Exact commands for each OS are on this page.

Is CVE-2025-53379 being exploited?

CVE-2025-53379 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-2025-53379 affect?

CVE-2025-53379 affects fortiauthenticator. Severity is high (CVSS 7.5). A out-of-bounds read vulnerability in Fortinet FortiAuthenticator 6.6.0 through 6.6.2, FortiAuthenticator 6.5 all versions may allow a remote unauthenticated attacker to retrieve sensitive information via a specially crafted request.

How urgent is CVE-2025-53379?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Software pages

Fortinet vulnerabilities

Related CVEs

CVE-2026-44277 CRITICAL 9.8 UPGRADE A improper access control vulnerability in Fortinet FortiAuthenticator 8.0.2, FortiAuthenticator 8.0.0, FortiA

References

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