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Two critical vulnerabilities have been discovered in Cisco's Snort 3 detection engine, affecting a wide range of Cisco products including Cisco Secure Firewall Threat Defense, open-source Snort 3, Cisco IOS XE with Unified Threat Defense, and Cisco Meraki appliances. These flaws, identified as CVE-2026-20026 and CVE-2026-20027, stem from improper handling of Distributed Computing Environment/Remote Procedure Call (DCE/RPC) requests, allowing unauthenticated remote attackers to either disrupt packet inspection services or extract sensitive information from affected systems. The vulnerabilities are particularly concerning for organizations running Snort 3 on Cisco Secure FTD releases 7.0.0 and later, where Snort 3 is enabled by default, significantly expanding the attack surface.
The first vulnerability (CVE-2026-20026) is a use-after-free condition that can trigger denial of service by causing unexpected engine restarts, while the second (CVE-2026-20027) is an out-of-bounds read that could lead to sensitive data leakage. Cisco has released software updates to address these issues, but no workarounds are available. The vulnerabilities can be exploited by sending specially crafted DCE/RPC requests through monitored network connections, and no authentication is required for exploitation, making internet-facing systems especially at risk. Organizations are urged to apply the available patches promptly to mitigate potential threats.
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2 events from the most recent confirmed update back to the earliest known activity.
Cisco made fixed software available, including Snort 3.9.6.0 and hot fixes for affected Secure Firewall Threat Defense releases. The vendor urged customers to upgrade promptly to mitigate the vulnerabilities.
Cisco published a security advisory for two critical Snort 3 Distributed Computing Environment/Remote Procedure Call vulnerabilities, CVE-2026-20026 and CVE-2026-20027. The flaws affect multiple Cisco products, including Secure Firewall Threat Defense, IOS XE with Unified Threat Defense, Meraki appliances, and open-source Snort 3, and could allow unauthenticated attackers to disrupt inspection or access sensitive information.
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A critical security vulnerability, CVE-2025-20352, has been identified in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS and IOS XE software, affecting a wide range of Cisco networking devices. This stack overflow flaw allows remote attackers with valid SNMP credentials to send specially crafted SNMP packets over IPv4 or IPv6, potentially causing denial-of-service (DoS) by forcing device reloads or, in more severe cases, enabling remote code execution as root. The vulnerability impacts all SNMP versions (v1, v2c, v3) and has been confirmed to affect both legacy and modern modular Cisco operating systems, including Meraki MS390 and Catalyst 9300 Series Switches running Meraki CS 17 and earlier. Reports indicate that up to 2 million devices globally, including those operated by ISPs and cloud providers, are potentially exposed to this vulnerability. The flaw was discovered during a Cisco Technical Assistance Center (TAC) support case and has already been exploited in the wild, prompting its addition to the CISA Known Exploited Vulnerabilities (KEV) catalog on September 29th, 2025. The exploitation of this vulnerability represents a significant escalation, as attackers have demonstrated the ability to gain administrator-level credentials and full device compromise. Rockwell Automation has issued an advisory confirming that its Lifecycle Services, specifically the Industrial Data Center (IDC) with Cisco Switching (Generations 1–5), are affected by this vulnerability. Rockwell has provided guidance on corrected software versions and available workarounds to mitigate the risk. The vulnerability poses a substantial threat to the backbone of enterprise, industrial, and service provider networks, given the widespread deployment of affected Cisco devices. Cisco’s response to the incident was initiated only after evidence of active exploitation emerged, underscoring the urgency of patching and mitigation. Organizations are strongly advised to update to the corrected Cisco software versions as soon as possible and to implement any recommended workarounds to reduce exposure. The incident highlights the ongoing risks associated with SNMP-enabled network infrastructure and the importance of credential management and network segmentation. Security teams should prioritize the identification of vulnerable devices and monitor for signs of exploitation. The rapid exploitation and large attack surface associated with CVE-2025-20352 make it a high-priority threat for organizations relying on Cisco networking equipment.
Jun 29, 2026
Cisco released security updates for 14 vulnerabilities in **Cisco IOS** and **Cisco IOS XE**, including the actively exploited zero-day **`CVE-2025-20352`**. The flaw is a stack overflow in the SNMP subsystem that can be triggered with crafted SNMP packets over IPv4 or IPv6. Cisco said a remote authenticated attacker can cause a denial of service, while an authenticated attacker with administrator privileges can escalate to remote code execution and full device compromise. Affected products include unpatched Cisco IOS and IOS XE devices, along with **Meraki MS390** and **Cisco Catalyst 9300 Series** switches running **Meraki CS 17 or earlier** when SNMP is enabled and vulnerable OIDs have not been explicitly disabled. Cisco urged organizations to use its **Software Checker** to identify exposure and apply fixes immediately; where patching is not yet possible, recommended mitigations include restricting SNMP access to trusted sources, disabling SNMP, or disabling vulnerable OIDs through device configuration.
Jul 24, 2026
Cisco released emergency fixes for two **critical (CVSS 10.0)** vulnerabilities in its firewall management software that could allow **remote, unauthenticated attackers** to execute code and gain **root-level** access to the underlying operating system. The issues are tracked as `CVE-2026-20079` and `CVE-2026-20131`, and reporting emphasized the risk profile given Cisco’s widespread deployment in large enterprises and the historical interest of sophisticated actors in rapidly weaponizing Cisco bugs. Available reporting stated there were **no confirmed in-the-wild exploitation** reports at the time of publication, but urged rapid patching due to the combination of unauthenticated reachability and full compromise potential. Separate coverage packaged the Cisco flaws alongside other weekly security items (e.g., Tycoon2FA infrastructure takedown and other incidents), but the Cisco item consistently described the same two maximum-severity firewall management vulnerabilities and their impact (RCE leading to root access).
Jun 29, 2026