Cisco warns of new SD-WAN zero-day exploited in attacks
Cisco says attackers are exploiting critical SD-WAN Manager auth-bypass zero-day CVE-2026-76504.
Authenticated Path Traversal File Overwrite in Cisco Catalyst SD-WAN Manager
CISA: Cisco Catalyst SD-WAN Manager Directory or Path Traversal Vulnerability
CVE-2026-20262 is a directory/path traversal vulnerability (CWE-22) in Cisco Catalyst SD-WAN Manager, the central management component of Cisco's enterprise SD-WAN solution. An authenticated, remote attacker can supply crafted input containing traversal sequences that escape the intended directory, allowing the attacker to create a new file or overwrite any file on the affected system's filesystem. Overwriting arbitrary files can enable configuration tampering, persistence, or privilege escalation on the management appliance depending on which file is targeted. Any organization running Cisco Catalyst SD-WAN Manager is affected, with greatest risk where the management interface is reachable by broad user populations or from the internet. CISA added the flaw to the Known Exploited Vulnerabilities catalog on 2026-06-15, indicating exploitation in the wild; no public proof-of-concept is known, ransomware association is unknown, CVSS is not yet scored, and EPSS assigns a 28.2% probability of exploitation within 30 days (98th percentile).
What to do: Apply the fixed release per Cisco's advisory (specific fixed versions are not provided in this data set, so consult Cisco's security notice) and follow CISA's KEV required action, including BOD 26-04 timelines for federal agencies and cloud service use. Until patched, restrict access to the SD-WAN Manager management interface to trusted management networks, enforce strong authentication, and audit the filesystem for unexpectedly created or recently modified files that could indicate exploitation. Evaluate each instance's internet exposure and prioritize internet-reachable management appliances for immediate remediation.
| Product | Affected |
|---|---|
| Cisco Catalyst SD-WAN Manager | — |
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
A vulnerability in the web UI of Cisco Catalyst SD-WAN Manager, formerly SD-WAN vManage, could allow an authenticated, remote attacker to create a file or overwrite any file on the filesystem of an affected system. This vulnerability exists because the affected software does not properly validate user-supplied input during a file upload process. An attacker could exploit this vulnerability by sending a crafted HTTP request to an affected API endpoint of the affected system. A successful exploit could allow the attacker to create or overwrite any file on the underlying operating system. This file could later be used to elevate to root. To exploit this vulnerability, the attacker must have valid credentials with at least a lower-privileged, single-task user account.
Cisco says attackers are exploiting critical SD-WAN Manager auth-bypass zero-day CVE-2026-76504.
Cisco reports active exploitation of critical CVE-2026-76504 (CVSS 9.8) unauthenticated authentication bypass in Catalyst SD-WAN Manager; patches released, no workaround.
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