CVE-2026-20118
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:HSummary
CVE-2026-20118 is a medium-severity Improper Cleanup on Thrown Exception (CWE-460) vulnerability in Cisco IOS XR (inferred from references). Its CVSS base score is 6.8 (Medium).
Operationally, ranked at the 24th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-24 (Fail in Known State) and SI-17 (Fail-safe Procedures) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-11224
Vulnerability Data
A vulnerability in the handling of an Egress Packet Network Interface (EPNI) Aligner interrupt in Cisco IOS XR Software for Cisco Network Convergence System (NCS) 5500 Series with NC57 line cards and Cisco NCS 5700 Routers and Cisco IOS XR…
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Software for Third Party Software could allow an unauthenticated, remote attacker to cause the network processing unit (NPU) and ASIC to stop processing, preventing traffic from traversing the interface. This vulnerability is due to the corruption of packets in specific cases when an EPNI Aligner interrupt is triggered while an affected device is experiencing heavy transit traffic. An attacker could exploit this vulnerability by sending a continuous flow of crafted packets to an interface of the affected device. A successful exploit could allow the attacker to cause persistent, heavy packet loss, resulting in a denial of service (DoS) condition. Note: If active exploitation of this vulnerability is suspected, contact the Cisco Technical Assistance Center (TAC) or your contracted maintenance provider. Cisco has assigned this security advisory a Security Impact Rating (SIR) of High rather than Medium as the score indicates. This change was made because the affected device operates within a critical network segment where compromise could lead to significant disruption or exposure, thereby elevating the overall risk beyond the base technical severity.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Requires the system to fail to a known state on indicated failures, directly forcing proper state cleanup instead of leaving inconsistent state after an exception.
Mandates explicit fail-safe procedures on failures, which structurally enforces cleanup actions that the weakness omits.
Requires application of security engineering principles (e.g., fail-safe, complete mediation) during design that would eliminate improper exception cleanup.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly enforce proper exception handling and resource cleanup.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect missing cleanup paths, thereby mitigating the weakness before deployment.
Secure SDLC mandates exception-handling and cleanup practices that reduce improper state after thrown exceptions.
Application security requirements can specify robust exception handling and resource-release rules.
Secure architecture principles include designing for safe failure and guaranteed cleanup on exceptions.
Secure coding standards directly require proper resource release and state restoration after exceptions.