OpenCATS through 0.9.5-3 unsafely deserializes index.php?m=activity requests, leading to remote code execution.

published 2021-01-18 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-12194

cvss: 9.8; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 11.3%; EPSS 11.3% chance of exploitation in 30 days, percentile 96%
public exploits: 0; none known

OpenCATS through 0.9.5-3 unsafely deserializes index.php?m=activity requests, leading to remote code execution. This occurs because lib/DataGrid.php calls unserialize for the parametersactivity:ActivityDataGrid parameter. The PHP object injection exploit chain can leverage an __destruct magic method in guzzlehttp.

Patch / fix

links 1

github.com/snoopysecurity/snoopysecurity.github.io/blob/master/web-ap… advisory

Exploit prediction

11.34% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

snoopysecurity.github.io https://snoopysecurity.github.io/web-application-security/2021/01/16/09_opencats_php_object_injection.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	9.8	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD	2.0	10.0	AV:N/AC:L/Au:N/C:C/I:C/A:C

Classification

Weakness

CWE-502 Deserialization of Untrusted Data

References

github.com /snoopysecurity/snoopysecurity.github.io/blob/master/web-application-security/2021/01/16/09_opencats_php_objec
patch, third-party-advisory
snoopysecurity.github.io /web-application-security/2021/01/16/09_opencats_php_object_injection.html
exploit, third-party-advisory
opencats.org /news/
vendor-advisory

Sources

CVE List CVE-2021-25294
NVD CVE-2021-25294

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary