CVE-2019-6503: There is a deserialization vulnerability in Chatopera cosin v3.10.0

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2019-6503 is a critical-severity flaw (CVSS 9.8) affecting cosin. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

There is a deserialization vulnerability in Chatopera cosin v3.10.0. An attacker can execute commands during server-side deserialization by uploading maliciously constructed files. This is related to the TemplateController.java impsave method and the MainUtils toObject method.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.2% (top 17%)
CISA exploited list	No
Weakness	CWE-502
Published	2019-01-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: chatopera

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

Am I affected?

Timeline

2019-01-22 14:29 UTCPublished CVE record published
2026-06-17 02:39 UTCUpdated Record last modified

chatopera cosin DOWNGRADE

Affected: 3.10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.10.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.10.0 (Debian / Ubuntu)

apt-cache madison cosin sudo apt install cosin=<VERSION_BEFORE_3.10.0> sudo apt-mark hold cosin

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

dnf --showduplicates list cosin sudo dnf downgrade cosin-<VERSION_BEFORE_3.10.0> sudo dnf versionlock add cosin

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-2019-6503?

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

Is CVE-2019-6503 being exploited?

CVE-2019-6503 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-2019-6503 affect?

CVE-2019-6503 affects cosin. Severity is critical (CVSS 9.8). There is a deserialization vulnerability in Chatopera cosin v3.10.0. An attacker can execute commands during server-side deserialization by uploading maliciously constructed files. This is related to the TemplateController.java impsave meth

How urgent is CVE-2019-6503?

Priority 65/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Java vulnerabilities

References

← Back to latest CVEs