CVE-2021-30137: Assyst 10 SP7.5 has authenticated XXE leading to SSRF via XML unmarshalling

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HIGH 7.7DOWNGRADE

CVE-2021-30137 is a high-severity flaw (CVSS 7.7) affecting assyst. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Assyst 10 SP7.5 has authenticated XXE leading to SSRF via XML unmarshalling. The application allows users to send JSON or XML data to the server. It was possible to inject malicious XML data through several access points.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.7 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-611
Published	2021-09-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: axiossystems

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-09-15 13:15 UTCPublished CVE record published
2026-06-17 03:49 UTCUpdated Record last modified

axiossystems assyst DOWNGRADE

Affected: 10 sp7.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 10

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 10 (Debian / Ubuntu)

apt-cache madison assyst sudo apt install assyst=<VERSION_BEFORE_10> sudo apt-mark hold assyst

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list assyst sudo dnf downgrade assyst-<VERSION_BEFORE_10> sudo dnf versionlock add assyst

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-2021-30137?

assyst: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-30137 being exploited?

CVE-2021-30137 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-2021-30137 affect?

CVE-2021-30137 affects assyst. Severity is high (CVSS 7.7). Assyst 10 SP7.5 has authenticated XXE leading to SSRF via XML unmarshalling. The application allows users to send JSON or XML data to the server. It was possible to inject malicious XML data through several access points.

How urgent is CVE-2021-30137?

Priority 45/100. High severity; Public exploit reference

References

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