Security Affairs newsletter Round 561 by Pierluigi Paganini

SolarWinds Web Help Desk contains a deserialization of untrusted data flaw (CWE-502) that allows an unauthenticated attacker to reach the vulnerable functionality over the network and have it deserialize attacker-supplied input. By sending crafted serialized data, the attacker triggers remote code execution and can run arbitrary commands on the host machine running Web Help Desk. Successful compromise grants control of the help desk server, and observed intrusions include attackers installing Zoho agents and Velociraptor for post-exploitation. Any organization running the product is affected, particularly instances exposed to the internet; the flaw carries a CVSS 9.8 (critical) score and federal agencies are under a CISA (BOD 22-01) patching deadline. The vulnerability is being actively exploited in the wild and was added to the CISA KEV catalog on 2026-02-03, with an EPSS probability of 83.6% that it will be exploited within 30 days.

Do: Upgrade Web Help Desk to the latest patched release per the SolarWinds security advisory (the source data does not specify a fixed version number), and follow BOD 22-01 mitigations or discontinue use if mitigation is not possible, noting the federal patching deadline. Until patched, restrict internet-facing access to the Web Help Desk server. Check hosts for post-exploitation artifacts reported in the wild, such as unexpected Zoho agent installations and Velociraptor, and review logs for unauthenticated requests targeting the application.

A path traversal flaw (CWE-35) in the Windows version of WinRAR allows attackers to achieve arbitrary code execution by delivering a specially crafted archive file that writes outside the expected location when it is opened or processed. Because the CVSS 4.0 vector indicates a local attack requiring user interaction, victims are typically infected by extracting or previewing a malicious archive received via phishing, a malicious download, or another delivery channel. A successful attacker gains the privileges of the user running WinRAR, providing an initial foothold that has been used for both espionage and ransomware operations. Anyone running the Windows version of WinRAR — one of the most widely deployed Windows desktop utilities — is affected, and CPE data additionally lists dtSearch as an affected vendor. Exploitation is confirmed in the wild by nation-state actors (e.g., the China-linked Amaranth-Dragon group per related reporting) and criminal actors including ransomware operators; the flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2025-08-12 and carries a near-maximal 94.6% EPSS score.

Do: Update WinRAR to the latest patched release from RARLAB on all Windows endpoints, prioritizing remediation per CISA KEV and BOD 22-01 requirements, and verify that dtSearch deployments bundling the affected component are also updated. Because exploitation requires a user to open or extract a crafted archive, warn users to treat unexpected archive files delivered by email or download with suspicion. Given confirmed ransomware use, hunt across user workstations — not just exposed servers — for suspicious archive-based infections and confirm the patched WinRAR version is installed.

CVE-2026-24858 is an authentication bypass (CWE-288) in FortiCloud single sign-on that lets an attacker who owns a FortiCloud account with any registered device log in to other customers' Fortinet devices that have FortiCloud SSO authentication enabled. It affects a wide range of 7.x/8.x builds of FortiOS, FortiProxy, FortiWeb, FortiAnalyzer, FortiManager, FortiNAC-F, and the Siemens RUGGEDCOM APE 1808. An attacker gains unauthorized access to devices registered to other accounts, and related reporting describes FortiGate devices being exploited to breach networks and steal service account credentials. Any organization running an affected build with FortiCloud SSO enabled is exposed. Exploitation is confirmed in the wild: CISA added the flaw to the KEV catalog on 2026-01-27 and Fortinet patched it after active FortiOS SSO exploitation was detected, and EPSS assigns an 86.1% probability of exploitation within 30 days.

Do: Upgrade all affected Fortinet products to the fixed releases specified in Fortinet's PSIRT advisory for CVE-2026-24858; as an interim mitigation, disable FortiCloud SSO authentication on affected devices and audit which devices are registered to your FortiCloud account. Review device logs for unexpected administrative logins or signs of service-account credential theft on FortiGate, and federal agencies must apply mitigations per BOD 22-01 (including CISA's cloud services guidance) or discontinue use of the product.