CVE-2026-53421: Improper Isolation or Compartmentalization vulnerability in Apache Syncope. An administrator with adequate

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CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-53421 is a critical-severity flaw (CVSS 9.8) affecting syncope. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper Isolation or Compartmentalization vulnerability in Apache Syncope. An administrator with adequate entitlements can achieve remote code execution through the connector subsystem by relying on scripted connectors' (REST and SQL) capability to run Groovy scripts. This issue affects Apache Syncope: from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 Through 4.0.6, from 4.1.0-M0 through 4.1.1. Users are recommended to upgrade to version 4.0.7

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-653
Published	2026-07-20
Last modified	2026-10-24

Publisher (CNA): Apache Software Foundation · Vendor: apache

Last updated 2026-10-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-20 15:16 UTCPublished CVE record published
2026-10-24 20:10 UTCUpdated Record last modified

apache syncope UPGRADE

Affected: >= 3.0.0 and <= 3.0.16 · >= 4.0.0 and < 4.0.7 · >= 4.1.0 and < 4.1.2

Fixed in: 4.0.7, 4.1.2

Safe to downgrade to: a release before 3.0.0

1. Check installed version

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

2. UPGRADE to 4.0.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade syncope

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 3.0.0 (Debian / Ubuntu)

apt-cache madison syncope sudo apt install syncope=<VERSION_BEFORE_3.0.0> sudo apt-mark hold syncope

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

dnf --showduplicates list syncope sudo dnf downgrade syncope-<VERSION_BEFORE_3.0.0> sudo dnf versionlock add syncope

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.

Exact fixes by distribution

Fedora 46 · conda · FIXED · 26.9.4-2.fc46 · FEDORA-2026-09931756f1 · source

sudo dnf upgrade --advisory=FEDORA-2026-09931756f1

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-2026-53421?

syncope: upgrade to 4.0.7, 4.1.2. Exact commands for each OS are on this page.

Is CVE-2026-53421 being exploited?

CVE-2026-53421 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-2026-53421 affect?

CVE-2026-53421 affects syncope. Severity is critical (CVSS 9.8). Improper Isolation or Compartmentalization vulnerability in Apache Syncope. An administrator with adequate entitlements can achieve remote code execution through the connector subsystem by relying on scripted connectors' (REST and SQL) c

How urgent is CVE-2026-53421?

Priority 64/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

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References

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