Authenticated RCE via Malicious eTemplate Upload in EGroupware

published 2026-07-07 4 mo ago modified 2026-09-10 1 mo ago also GHSA-8737-2x9g-xjj7 , EUVD-2026-46033

cvss: 8.6; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 58%
public exploits: 0; none known

In egroupware version 26.0 and earlier, an authenticated administrator can achieve OS-level Remote Code Execution (RCE) by uploading a malicious eTemplate XML file (`.xet`) to the VFS `/etemplates` mount. The `Widget::expand_name()` method passes template widget attribute values directly into a PHP `eval()` call with only double-quote escaping applied - **backtick characters are not escaped**. In PHP, backticks inside a double-quoted `eval()` string execute shell commands. This allows an admin-level user to escalate from web application access to arbitrary OS command execution on the server.

Patch / fix

fixed in 1

packagist egroupware/egroupware 23.1.20260601, 26.4.20260413

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: total
Assessed: 3 mo ago (2026-07-20)

Exploit prediction

0.86% chance of exploitation in the next 30 days, higher than 58% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/EGroupware/egroupware/security/advisories/GHSA-8737-2x9g-xjj7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA	4.0	8.6	CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected packages

ecosystem	package	affected	fixed in
packagist	egroupware/egroupware	>=26.0.20251208, <26.4.20260413 <23.1.20260601	26.4.20260413 23.1.20260601

Affected products

EGroupware egroupware

Classification

Weakness

CWE-78 Improper Neutralization of Special Elements used in an OS Command
CWE-95 Improper Neutralization of Directives in Dynamically Evaluated Code

References

github.com /EGroupware/egroupware/security/advisories/GHSA-8737-2x9g-xjj7
exploit, web
github.com /EGroupware/egroupware
package

Sources

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