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CVE-2026-34838 affects Group-Office, an enterprise CRM and groupware platform. In versions prior to 6.8.156, 25.0.90, and 26.0.12, the AbstractSettingsCollection model insecurely deserializes settings data when loading stored settings. An authenticated attacker can inject a serialized FileCookieJar object into a setting string, causing unsafe object deserialization. This can be abused to perform arbitrary file write operations on the server, which in turn can be leveraged to achieve remote code execution.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a small, focused exploit PoC consisting of a README and a single Python script, poc.py. The script targets Group-Office and implements an authenticated web exploit for the deserialization issue referenced as GHSA-h22j-frrf-5vxq / CVE-2026-34838. Its purpose is to log into a vulnerable instance, store a crafted serialized PHP object into an application setting, and then trigger a code path that unserializes that setting during export operations. The exploit structure is straightforward: configuration constants define the target URL, credentials, payload path, and PHP command-execution stub; helper functions build raw PHP serialized values; build_gadget_chain() constructs a GuzzleHttp\Cookie\FileCookieJar gadget chain; login() authenticates and extracts a security_token from the application HTML; step1_store() sends the malicious serialized value to core/saveSetting under the export_include_headers key; and step2_trigger() requests one of several export routes to force GO.Base.Export.Settings to load and deserialize the attacker-controlled value. Main capability: authenticated remote code execution through PHP object deserialization. The immediate technical action performed by the gadget chain is arbitrary file write using FileCookieJar->__destruct() -> save() -> file_put_contents(). The written content embeds PHP code: <?php system($_GET[0]); ?>. In the provided configuration, the file is written to /tmp/shell.php, which the author notes is writable but not web-accessible, so the PoC as configured primarily demonstrates arbitrary file write and the viability of the RCE chain rather than guaranteed interactive command execution. If the write path were changed to a web-accessible location, the payload would function as a command-execution webshell. There is no evidence this is part of a larger exploit framework. It is a standalone Python PoC using the requests library. The code is operational rather than merely demonstrative because it performs real authentication, payload delivery, and trigger requests against live endpoints.
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