2026-06-06 · view entry permalink →
CVE-2026-20245, Cisco Catalyst SD-WAN Manager: actively-exploited command-injection to root (no patch)
Cisco has confirmed a second actively-exploited zero-day in Catalyst SD-WAN Manager (formerly vManage), tracked as CVE-2026-20245 (Cisco PSIRT; NCSC-CH GovCERT, 2026-06-05). It is a command-injection flaw: an attacker with netadmin privileges can inject arbitrary OS commands that execute as root on the underlying appliance (T1059.004 Unix Shell, following T1078 Valid Accounts). Per Cisco, exploitation requires either valid netadmin credentials or prior exploitation of the pre-auth bypass CVE-2026-20182 (covered in weekly W22) or CVE-2026-20127, making the realistic path an unauthenticated-to-root chain against an internet-exposed Manager. Cisco states it has "observed limited cases where the exploitation of this bug resulted in a configuration change pushed to edge devices," i.e. the blast radius extends from the management plane to every managed edge router. No fixed release is available; Cisco's only guidance is to restrict management-plane access to trusted hosts and verify edge-device configuration. Detection concepts: review the SD-WAN Manager CLI audit log for unexpected command execution and EDR/host telemetry for shells spawned under the management daemon's service account; treat any unplanned config push to edge devices as a hunting trigger. Hardening: ACL the management interface to a dedicated management VLAN, enforce MFA for netadmin, and rotate Manager credentials given confirmed in-the-wild use.
Cisco has confirmed a second actively-exploited zero-day in Catalyst SD-WAN Manager (formerly vManage), tracked as CVE-2026-20245 (Cisco PSIRT; NCSC-CH GovCERT, 2026-06-05).
UPDATE (originally covered 2026-06-06): When we first noted CVE-2026-20245 it was a fresh Cisco advisory for a command-injection-to-root flaw in Catalyst SD-WAN Manager with confirmed exploitation but little public detail.
UPDATE (originally covered 2026-06-26): Google Mandiant (GTIG) published (2026-06-24) the first complete TTP chain for the Cisco Catalyst SD-WAN Manager zero-day activity, observed at a service-provider victim from late 2025 into 2026 (Google Mandiant, 2026-06-24).
When we first noted CVE-2026-20245 it was a fresh Cisco advisory for a command-injection-to-root flaw in Catalyst SD-WAN Manager with confirmed exploitation but little public detail. Mandiant/GTIG has now published the forensic reconstruction, confirming the flaw was used as a zero-day at a communications service provider from late 2025 through March 2026, months before the patch (Mandiant/GTIG, 2026-06-24).
The new substance is the kill chain: a peering-authentication-bypass foothold (CVE-2026-20127 / CVE-2026-20182) into SSH as vmanage-admin, then a crafted tenant CSV through the request tenant-upload CLI handler injecting commands that planted a backdoor troot UID-0 account, with anti-forensic clean-up (admin-password change-then-revert, history/syslog deletion). Mandiant names no threat actor. Full mechanics, ATT&CK mapping and host-level detection are in §5.
Google Mandiant (GTIG) published (2026-06-24) the first complete TTP chain for the Cisco Catalyst SD-WAN Manager zero-day activity, observed at a service-provider victim from late 2025 into 2026 (Google Mandiant, 2026-06-24). NCSC-CH amended its Security Hub post to add the report on 2026-06-25 (NCSC-CH Security Hub post 12579).
The chain: authentication bypass via CVE-2026-20182/CVE-2026-20127 (rogue peering connection), then privilege escalation via CVE-2026-20245; a malicious evil_tenant.csv uploaded through the request tenant-upload CLI carries unsanitised shell commands that append a troot root user to /etc/passwd and /etc/shadow, after which the actor reverts configuration changes and deletes the file for anti-forensics. This gives defenders concrete hunts the earlier advisory could not: search SD-WAN Manager instances for unexpected /etc/passwd additions, evil_tenant.csv artefacts, and request tenant-upload execution in CLI logs.