As part of Cisco's ongoing commitment to proactive security and product quality, engineering teams for Cisco Emergency Responder, Cisco Prime Collaboration Deployment, Cisco Unified Communications Manager (Unified CM), Cisco Unified Communications Manager IM & Presence Service (Unified CM IM&P), Cisco Unified Communications Manager Session Management Edition (Unified CM SME), and Cisco Unity Connection have conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities.
The vulnerabilities tracked by CVE-2026-76473 are related to issues concerning improper control of a resource through its lifetime that are grouped under the Common Weakness Enumeration (CWE) Class CWE-74.
A vulnerability in Cisco Expressway Series could allow an unauthenticated, remote attacker to obtain sensitive information from an affected device.
This vulnerability is due to insufficient authorization checks of HTTP requests during Mobile and Remote Access (MRA) provisioning. An attacker could exploit this vulnerability by submitting a crafted URL request to an affected device. A successful exploit could allow the attacker to access sensitive information that they would otherwise not have authorization to access.
Note: Cisco Expressway Series refers to Cisco Expressway Core (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices.
A vulnerability in the database service feature of Cisco Expressway Series could allow an unauthenticated, remote attacker with network access to a Cisco Expressway device to execute arbitrary operating system commands as root.
This vulnerability is due to the use of persistent cookies. Additionally, there is insufficient validation of client certificates when the TLS Verify Mode is set to Enabled for clustering, which means that client certificates are not validated. An attacker with possession of the cookies could exploit this vulnerability by connecting to the database service and invoking specific remote procedure call (RPC) commands. A successful exploit could allow the attacker to execute arbitrary commands as root on the underlying operating system of an affected device.
Note: Cisco Expressway Series refers to Cisco Expressway Core (Expressway-C) devices and Cisco Expressway Edge (Expressway-E) devices.
A vulnerability in the interprocess communication (IPC) channel of the Secure Firewall Posture module in Cisco Secure Client could allow an authenticated, local attacker to elevate privileges on an affected device.
This vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by sending a series of crafted IPC messages to a local socket. A successful exploit could allow the attacker to perform limited file write operations on the filesystem with SYSTEM or root privileges.
Although this vulnerability affects the Secure Firewall Posture module in Cisco Secure Client on Windows, macOS, and Linux operating systems, this vulnerability could be used to obtain full root privileges on macOS and Linux. For that reason Cisco has assigned this security advisory a Security Impact Rating (SIR) of High rather than Medium as the score indicates.
CVE-2026-20356 is a high-severity vulnerability in Cisco Cyber Vision involving uncontrolled resource consumption. It was identified during an internal security review by Cisco's Snort 3 engineering team. The issue can lead to denial of service by exhausting system resources. Multiple specific versions of Cisco Cyber Vision are affected. No known exploits are reported in the wild. No patch or remediation details are provided in the input data.
CVE-2026-20236 is a high severity vulnerability in Cisco Cyber Vision involving incorrect calculation issues. These issues fall under the CWE-682 category and were identified during an internal security review by Cisco's Snort 3 Software engineering team. The vulnerability impacts multiple specific versions of Cisco Cyber Vision. The CVSS score of 7.5 indicates a high severity with network attack vector, low attack complexity, no privileges required, no user interaction, and an impact limited to availability. There are no known exploits in the wild and no vendor advisory or patch information is provided.
CVE-2026-20221 is a medium severity vulnerability in Cisco Cyber Vision affecting multiple versions. It involves a NULL pointer dereference in the Snort 3 Detection Engine's handling of nested GRE tunnel decapsulation. An unauthenticated remote attacker can send crafted GRE payloads to trigger an unexpected restart of the detection engine, causing denial of service or bypass conditions depending on configuration. The Snort 3 Detection Engine restarts automatically without manual intervention.
CVE-2026-20291 is a high-severity vulnerability in Cisco Cyber Vision involving improper privilege management. It affects multiple specific versions of the product. The flaw allows an attacker with limited privileges to potentially gain elevated access, impacting confidentiality, integrity, and availability. No known exploits are reported in the wild. Cisco has conducted internal security reviews and released software hardening updates addressing these issues.
CVE-2026-20197 is a medium severity vulnerability in Cisco Open Source Snort3 affecting multiple versions. It involves improper restriction of operations within the bounds of a memory buffer in the Snort 3 Teredo Detection Engine. An unauthenticated remote attacker can send crafted Teredo packets that cause the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS) condition by interrupting packet inspection.
CVE-2026-20218 is a stack-based buffer overflow vulnerability in the Snort 3 Visual Basic for Applications (VBA) Decompression Engine used by multiple Cisco products. An unauthenticated remote attacker can exploit this flaw by sending specially crafted VBA data to the Snort 3 Detection Engine, causing it to restart unexpectedly and resulting in a denial of service (DoS). This vulnerability arises from improper range checking during VBA data decompression. The issue affects multiple specific versions of Cisco Open Source Snort3.
A vulnerability in Cisco Open Source Snort3's GRE Detection Engine allows unauthenticated remote attackers to cause the detection engine to restart by sending crafted GRE packets. This results in a denial-of-service (DoS) condition due to interruption of packet inspection.
CVE-2026-20043 is a critical vulnerability in Cisco Cyber Vision involving out-of-bounds write issues. These vulnerabilities were identified during an internal security review by Cisco's Snort 3 Software engineering team and relate to CWE-787. The flaw affects multiple specific versions of Cisco Cyber Vision. The CVSS v3.1 score is 9.0, indicating high impact on confidentiality, integrity, and availability. No public exploits are known, and no patch or remediation details are provided in the input data.
CVE-2026-20019 is a medium severity vulnerability in Cisco Open Source Snort3 affecting multiple versions. It involves an infinite loop caused by incomplete error checking when parsing UDP Netflow Protocol packets. An unauthenticated remote attacker can exploit this by sending a crafted Netflow packet, causing the Snort 3 Detection Engine to restart unexpectedly and resulting in a denial-of-service (DoS) condition.
CVE-2026-20011 is a medium severity vulnerability in Cisco Open Source Snort3 affecting multiple versions. It involves a buffer access issue with incorrect length values in the Snort 3 SMTP MIME Decoder. An unauthenticated remote attacker can exploit this by sending crafted SMTP packets, causing the Snort 3 Detection Engine to restart unexpectedly, resulting in a denial of service (DoS).
A recursive BIND server that receives a query with recursion desired (RD=1) followed by a non-recursive query (RD=0) may exit with an assertion failure, resulting in a denial of service. To be vulnerable, the BIND server must allow recursive queries and have at least two RPZ zones configured: one with the default setting of "recursive-only yes", and the other with "recursive-only no".
This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.
A BIND resolver that is configured with both a "redirect" zone and "qname-minimization strict" may abort with an assertion failure while processing the redirect.
This issue affects BIND 9 versions 9.16.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.16.8-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.
Replaying GSS-TSIG signed UDP messages can result in memory corruption in "`named`". An attacker who can capture a previously signed UDP message can replay it while the negotiated TSIG key is still valid. By also sending crafted queries to a zone the attacker controls, the attacker may potentially achieve remote code execution.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.
In a BIND resolver, inbound DNS protocol messages with a particular structure will result in additional processing, with no limit imposed by BIND. A DNS message with a maliciously large number of such structures will cause BIND to consume disproportionate amounts of CPU time and memory during processing.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.
CVE-2026-57447 is a medium severity vulnerability in the discourse-doc-categories plugin for Discourse. The issue involves exposure of sensitive information where the doc category index refresh resolves linked titles for private messages or restricted category topics without enforcing viewer authorization. This allows a user with permission to edit the index topic to learn titles of topics they are not authorized to view, though access to the topic contents is not granted. The vulnerability has been addressed by a specific commit in the source code.
CVE-2026-55103 is a vulnerability in the discourse-activity-pub plugin for Discourse that allows remote attackers to edit, delete, or reply to federated posts without proper permissions due to insufficient verification of the actor's identity and ownership of the post. This issue was fixed in commit 1c8518b0f2abdf31cbea3e0b242f74d8994a9ba5. The vulnerability has a high severity with a CVSS score of 8.6.