Authenticated PHP Object Deserialization RCE in Roundcube Webmail
CISA: RoundCube Webmail Deserialization of Untrusted Data Vulnerability
CVSS 3.1
8.8high
EPSS
99%p100
Published
()
KEV added
AI analysis
Roundcube Webmail before 1.5.10 and 1.6.x before 1.6.11 contains a PHP object deserialization flaw (CWE-502) that allows remote code execution by authenticated users. The bug is in program/actions/settings/upload.php, where the _from URL parameter is not validated before deserialization, so any logged-in user can trigger it with a crafted URL to the settings upload action, with no user interaction required. Successful exploitation gives the attacker code execution on the web server with high confidentiality, integrity, and availability impact (CVSS 3.1 8.8). All deployments running affected versions are exposed, including Roundcube packages shipped with Debian Linux. The flaw reportedly existed for roughly a decade before disclosure, carries a 98.9% EPSS score (top percentile), and was added to CISA's KEV catalog on 2026-02-20, confirming exploitation in the wild.
What to do: Upgrade to Roundcube 1.6.11 or 1.5.10 (or later); Debian administrators should install the fixed roundcube package via security updates. Hunt for compromise by reviewing web access logs for requests to the settings upload action with unusual or crafted _from parameters, and check the web server runtime for unexpected processes, files, or webshells. Federal agencies must apply mitigations per vendor instructions under BOD 22-01 or discontinue use of the product if mitigations are unavailable.
Affected
Roundcube Webmail
all versions before 1.5.10, and 1.6.x before 1.6.11
masslikely tens of thousands of internet-exposed Roundcube instances serving millions of mailboxes — Roundcube is the bundled/default webmail client for many hosting and mail platforms and is packaged in Debian, and public internet scans consistently surface tens of thousands of exposed instances that in aggregate serve well over one…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description
Roundcube Webmail before 1.5.10 and 1.6.x before 1.6.11 allows remote code execution by authenticated users because the _from parameter in a URL is not validated in program/actions/settings/upload.php, leading to PHP Object Deserialization.
CISA Known Exploited Vulnerability
Affected
Roundcube Webmail
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Check Point links Lazarus Group's Operation Dream Job to a new Windows zero-day, CVE-2026-68820, targeting defense workers with fake Lockheed Martin job offers.
Check Point Research documented a new wave of Operation Dream Job, a North Korean Lazarus Group campaign targeting defense and aerospace professionals in France, Germany, Brazil, and India with fake Lockheed Martin job offers. The attacks chain a previously unknown Windows privilege escalation flaw in AFD.sys, CVE-2026-68820, which Microsoft patched on August 11, 2026, to deploy the MISTPEN downloader, ForestTiger backdoor, and updated FudModule 3.1 kernel rootkit. Check Point also discovered a new Troy backdoor DLL with 17 operator commands and a RelayShell PHP webshell deployed on compromised Roundcube and WordPress servers used as command relays, some infected via CVE-2025-49113 or leaked credentials. Defenders are urged to apply the August 2026 Patch Tuesday update and review Check Point's indicators of compromise.
Lazarus' Operation Dream Job targets the defense sector with fake job offers, a Windows LPE zero-day (CVE-2026-68820), and new Troy and RelayShell backdoors.
Check Point documented two parallel infection chains in Lazarus' Operation Dream Job: a digitally signed PDF viewer with DLL sideloading delivering the MISTPEN in-memory downloader, and a trojanized SecurityPDF viewer, distributed via fake Enveil websites, installing the newly documented Troy backdoor. A component exploits CVE-2026-68820, a local privilege escalation zero-day in the Windows AFD.sys driver used since at least early July, which Microsoft patched on August 11, 2026, enabling deployment of the FudModule kernel-mode rootkit. Lazarus also compromised Roundcube webmail servers vulnerable to CVE-2025-49113 to deploy the RelayShell PHP web shell and relay C2 traffic, targeting defense-sector organizations primarily in Western Europe and India. Separately, CERT-UA documented Sandworm's UAC-0145 using fake job offers against IT professionals since May 2026.
Lazarus exploits Windows AFD.sys zero-day CVE-2026-68820 in Operation Dream Job to deploy Troy backdoor at defense firms.
Check Point attributes Operation Dream Job attacks to Lazarus Group exploiting CVE-2026-68820 (CVSS 7.0), a privilege escalation flaw in Windows AFD.sys patched in August 2026 Patch Tuesday. The campaign targets defense and aerospace firms in France, Germany, Brazil, and India via trojanized PDF viewers and DLL side-loading, deploying backdoors Troy, ForestTiger, and the FudModule 3.1 kernel rootkit. Attackers also compromise WordPress, SharePoint, and Roundcube servers as C2, using CVE-2025-49113 and the RelayShell PHP web shell.