A flaw in Cisco Unified Communications Manager, the system that runs enterprise phone and call infrastructure, is now being exploited in attacks. The bug (CVE-2026-20230) is a server-side request forgery that lets an unauthenticated attacker send a crafted HTTP request to write files onto the underlying system, which can then be used to escalate to root and fully take over the server. Cisco patched it on June 3 and rates it critical; public exploit code has been available since, and security firms now see active exploitation attempts. The flaw is only exploitable when the WebDialer service is enabled, which is not the default.
Cisco has patched serious flaws in Identity Services Engine (ISE), the platform many organizations use to control who and what connects to their network. The most severe is a critical remote-code-execution bug that can give an attacker root-level control of the appliance. A second flaw, CVE-2026-20190, is an unauthenticated information-disclosure issue caused by weak authorization checks, letting a remote attacker pull sensitive data, including hashed credentials, that could fuel follow-on attacks and lateral movement. All versions of ISE and ISE-PIC are affected, though which flaws apply varies by release. Cisco has not reported active exploitation, but ISE sits at the heart of network access control.
Cisco has patched a flaw in Catalyst SD-WAN Manager (formerly vManage), the console used to manage thousands of SD-WAN devices, that attackers were already exploiting as a zero-day to gain root. The bug (CVE-2026-20262) stems from weak validation of file uploads in the web interface, letting an authenticated low-privilege remote attacker create or overwrite any file on the system by sending crafted HTTP requests, and from there run commands as root. It affects every deployment type, including on-premises, Cisco-managed cloud, and the FedRAMP government edition, regardless of configuration. It is the latest in a run of exploited Cisco SD-WAN Manager zero-days this year.
Cisco has warned of an actively exploited, unpatched zero-day in Cisco Catalyst SD-WAN Manager (CVE-2026-20245) that enables root privilege escalation across all deployment types, including on-prem, Cloud, Managed, and FedRAMP Government. The flaw stems from insufficient validation of user-supplied input: an attacker who uploads a crafted file can perform command injection and run arbitrary commands as root. Exploitation requires netadmin privileges - obtained via valid credentials or by chaining CVE-2026-20182 or CVE-2026-20127. Mandiant reported the activity to Cisco's PSIRT in June. Cisco has observed limited cases where exploitation pushed configuration changes to edge devices, and published IoCs pointing to suspicious tenant-list uploads in scripts.log.
Cisco has patched CVE-2026-20230, a critical server-side request forgery flaw in Unified Communications Manager (formerly CallManager), the central control system for Cisco IP telephony. An unauthenticated remote attacker can send a crafted HTTP request to write files to the underlying OS and later elevate to root - Cisco rated it Critical despite the CVSS score because of that root-escalation potential. Cisco's PSIRT is aware of public proof-of-concept exploit code but has not seen active exploitation yet. The flaw only affects systems with the WebDialer service enabled, which is off by default. There are no workarounds; admins should upgrade to 14SU6 or 15SU5, or disable WebDialer until patched.
Cisco has patched a maximum-severity flaw, CVE-2026-20223, in the internal REST APIs of Cisco Secure Workload (formerly Tetration), the zero-trust microsegmentation platform used to stop lateral movement in enterprise environments. Insufficient authentication on the affected endpoints lets an unauthenticated remote attacker craft a request that returns sensitive data and modifies configuration with Site Admin privileges across tenant boundaries. Cisco's PSIRT says there is no evidence of in-the-wild exploitation yet and no workaround exists. The on-prem fixed releases are 3.10.8.3 and 4.0.3.17; the SaaS deployment has already been patched. Sites running 3.9 or earlier must migrate to a fixed release.
Cisco disclosed and patched a second perfect-score authentication bypass in its Catalyst SD-WAN Controller and Manager (formerly vSmart and vManage). The bug, CVE-2026-20182 (CVSS 10.0), was found by Rapid7 while investigating the earlier CVE-2026-20127 wave, and lives in the same vdaemon service over DTLS port 12346. An unauthenticated attacker can become a trusted peer of the controller, log in as a privileged internal account, hit the NETCONF interface, and rewrite the entire SD-WAN fabric. Cisco Talos already attributes limited in-the-wild exploitation to UAT-8616, an actor with operational-relay-box ties that has been targeting Cisco SD-WAN since 2023.
Cisco patched a high-severity denial-of-service flaw in Cisco Crosswork Network Controller (CNC) and Cisco Network Services Orchestrator (NSO) that lets unauthenticated remote attackers exhaust connection resources and force the system into an unresponsive state. CVE-2026-20188. Recovery requires manual reboot. Cisco's PSIRT has not seen exploitation in the wild yet, but Cisco previously patched similar DoS bugs (CVE-2025-20362, CVE-2025-20333) that ended up being weaponized to force ASA and FTD firewalls into reboot loops, which CISA addressed with an emergency directive in November 2025.
CISA and the UK's National Cyber Security Centre jointly published a malware analysis report for FIRESTARTER, a persistent backdoor that China-linked group UAT-4356 (the same crew behind 2024's ArcaneDoor campaign) planted on Cisco ASA and Firepower firewall devices by chaining CVE-2025-20333 (VPN web server RCE) and CVE-2025-20362 (unauthorized access). The implant hooks into Cisco's Service Platform mount list, a boot-time configuration that controls which programs run when the device starts, so it survives reboots, firmware upgrades, and the September 2025 patches for those two CVEs. CISA found FIRESTARTER on an already-patched US federal civilian agency's Cisco Firepower device through continuous network monitoring - attackers silently returned in March 2026 to deploy a second-stage implant called Line Viper without needing to re-exploit the original vulnerabilities. Updated Emergency Directive ED 25-03 now orders federal agencies to audit every Cisco ASA and Firepower device they run and submit device memory snapshots for CISA analysis. The stark guidance for everyone else: if you confirm a compromise, replace the hardware. Reimaging is not enough because the bootloader itself may be implanted.
CISA added a Cisco Catalyst SD-WAN Manager information disclosure flaw to its Known Exploited Vulnerabilities catalog on Monday, ordering federal agencies to patch by Friday, April 24 - an unusually aggressive 4-day deadline that reflects confirmed active exploitation. CVE-2026-20133 is an unauthenticated remote flaw in the SD-WAN Manager (formerly vManage) API, caused by insufficient file system access restrictions. An attacker can access the API and read sensitive information from the underlying operating system - including credentials that enable follow-on attacks. Cisco patched it in late February alongside two other SD-WAN Manager flaws (CVE-2026-20128 and CVE-2026-20122, both also added to KEV this week and confirmed exploited in the wild). Catalyst SD-WAN Manager is used to centrally manage up to 6,000 SD-WAN devices from one dashboard, making it a high-value target. Oddly, Cisco's PSIRT still says they have no evidence of public exploitation - contradicting CISA. CISA is treating its own intelligence as authoritative and has issued Emergency Directive 26-03 plus a Hunt & Hardening Guide for Cisco SD-WAN. Over the past several years CISA has tagged 91 Cisco vulnerabilities as exploited in the wild, six used by ransomware operations.
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