CVE-2026-27760: opencats OpenCATS

OpenCATS PHP Code Injection via installer AJAX endpoint

CVSS 9.2 CriticalCriticalEPSS 0.33 · 98th percentile

Critical, because:

CVSS score 9.2: 9.0 or more.
CVSS score 9.2 (7.0 or more) and EPSS 0.33 (0.1 or more): a high score and a real chance of exploitation in the next 30 days.

Published by the CVE Program (CNA: VulnCheck) at 28 Apr 2026, 13:43 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

Affected products, as the CNA wrote them
Vendor	Product	Versions
opencats	OpenCATS pkg:github/opencats/OpenCATS	affected 0.9.7.4 and earlier custom unaffected 3002a29f4c3cada1aa2c4f3d4ae4e189906606b6 git Other versions: unaffected

Identifiers

CVE-2026-27760

CNA

VulnCheck

Weakness (CWE)

CWE-94

Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
9.2	Critical	4.0	CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	CNA (VulnCheck)Used for this record
8.1	High	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H	CNA (VulnCheck)

CISA KEV Not listed.
EPSS 0.33, the 98th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the CVE Program, published 28 Apr 2026. New records show when each source confirmed them.

Sources

References from the CNA

github.com/opencats/OpenCATS/pull/706 issue-tracking
github.com/opencats/OpenCATS/commit/3002a29f4c3cada1aa2c4f3d4ae4e189906606b6 patch
github.com/opencats/OpenCATS/blob/46e4727/lib/CATSUtility.php#L142-L172 related
github.com/opencats/OpenCATS/blob/46e4727/modules/install/ajax/ui.php#L130 related
www.vulncheck.com/advisories/opencats-php-code-injection-via-installer-ajax-endpoint third-party-advisory
chocapikk.com/posts/2026/opencats-installer-rce/ technical-descriptionexploit

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.