Description

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XR Software engineering team has conducted a comprehensive internal security review. This review resulted in a software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20274 are related to improper resource control issues that are grouped under the Common Weakness Enumeration (CWE) CWE-664.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-02T17:17:32.630Z",
  "pubdate": "2026-09-02T17:17:32.630Z",
  "executiveSummary": "The vulnerability tracked as CVE-2026-20274 affects Cisco IOS XR Software and is classified under CWE-664 (Improper Control of a Resource Through its Lifetime). This security flaw stems from insufficient resource management within the software architecture, potentially allowing for improper allocation or release of system resources.\nThe primary risk associated with this vulnerability is the compromise of system availability. By exploiting the resource control mechanism, an attacker could induce a state of resource exhaustion, leading to a denial-of-service (DoS) condition on the affected device. This may manifest as process instability, service degradation, or complete system unresponsiveness.\nGiven that this vulnerability was identified during an internal security review, it emphasizes the importance of robust resource accounting and lifecycle management within the IOS XR kernel and its associated processes. Organizations utilizing Cisco IOS XR should evaluate their exposure and prioritize the application of provided software hardening releases to remediate these underlying structural deficiencies.",
  "technicalDetails": "CVE-2026-20274 is rooted in a failure to adequately manage the lifecycle of system resources, falling under the CWE-664 classification. In the context of Cisco IOS XR, this typically indicates that specific internal processes or subsystems fail to correctly handle the allocation, reclamation, or protection of shared memory, buffers, or process execution threads. When an object or resource is initialized but not correctly tracked or released upon the termination of a process or a specific event trigger, it results in a resource leak or an inconsistent state.\nThe attack flow for such an issue generally involves a deliberate attempt to trigger the vulnerable code path repeatedly. An attacker could send specially crafted traffic or malformed control plane packets that force the device to allocate specific resources—such as memory buffers or table entries—without providing the necessary signaling or completion state to allow the system to reclaim those resources. Because the resource control logic is flawed, the device fails to garbage collect or decrement the reference counters associated with these objects.\nOver time, the accumulation of these orphaned resources leads to resource exhaustion. As the available memory or process handles reach depletion thresholds, the IOS XR system may trigger internal protection mechanisms or experience critical process failures, such as kernel panics or service crashes, effectively resulting in a denial-of-service. Because this involves resource management, the exhaustion can often be sustained with low-bandwidth, repetitive requests that maximize the discrepancy between allocation rates and reclamation rates.\nThe vulnerable components reside within the core software architecture of Cisco IOS XR. While specific authentication or privilege requirements are often dependent on the reachable attack surface, these issues typically affect the control plane. If an attacker has network access to the management plane or the ability to influence control plane traffic, they can potentially trigger the resource management failure remotely. Exploitation does not necessarily require the attacker to execute arbitrary code; rather, it relies on manipulating the software's state machine to induce an unrecoverable resource management error. Post-exploitation, the impact remains restricted to the denial of system services until a manual reset or automated recovery sequence is initiated."
}