Vulnerability Database

393,392

Total vulnerabilities in the database

CVE-2024-20309 — cisco / ios_xe

Signal Handler with Functionality that is not Asynchronous-Safe

A vulnerability in auxiliary asynchronous port (AUX) functions of Cisco IOS XE Software could allow an authenticated, local attacker to cause an affected device to reload or stop responding.

This vulnerability is due to the incorrect handling of specific ingress traffic when flow control hardware is enabled on the AUX port. An attacker could exploit this vulnerability by reverse telnetting to the AUX port and sending specific data after connecting. A successful exploit could allow the attacker to cause the device to reset or stop responding, resulting in a denial of service (DoS) condition.

  • Published: Mar 27, 2024
  • Updated: Oct 2, 2026
  • CVE: CVE-2024-20309
  • Severity: Medium
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: Medium
  • Score: 5.6
  • AV:L/AC:H/PR:L/UI:N/S:C/C:N/I:N/A:H

CWEs:

Software Affected versions
cisco / ios_xe = 3.2.0se
cisco / ios_xe = 3.2.1se
cisco / ios_xe = 3.2.2se
cisco / ios_xe = 3.2.3se
cisco / ios_xe = 3.3.0se
cisco / ios_xe = 3.3.0sq
cisco / ios_xe = 3.3.1se
cisco / ios_xe = 3.3.1sq
cisco / ios_xe = 3.3.2se
cisco / ios_xe = 3.3.3se
cisco / ios_xe = 3.3.4se
cisco / ios_xe = 3.3.5se
cisco / ios_xe = 3.4.0sq
cisco / ios_xe = 3.4.1sq
cisco / ios_xe = 3.5.0sq
cisco / ios_xe = 3.5.1sq
cisco / ios_xe = 3.5.2sq
cisco / ios_xe = 3.5.3sq
cisco / ios_xe = 3.5.4sq
cisco / ios_xe = 3.5.5sq
cisco / ios_xe = 3.5.6sq
cisco / ios_xe = 3.5.7sq
cisco / ios_xe = 3.5.8sq
cisco / ios_xe = 3.6.2ae
cisco / ios_xe = 3.6.2e
cisco / ios_xe = 3.6.5be
cisco / ios_xe = 3.6.7be
cisco / ios_xe = 3.6.9e
cisco / ios_xe = 3.6.10e
cisco / ios_xe = 3.7.0bs
cisco / ios_xe = 3.7.0s
cisco / ios_xe = 3.7.1as
cisco / ios_xe = 3.7.1s
cisco / ios_xe = 3.7.2s
cisco / ios_xe = 3.7.2ts
cisco / ios_xe = 3.7.3s
cisco / ios_xe = 3.7.4as
cisco / ios_xe = 3.7.4s
cisco / ios_xe = 3.7.5s
cisco / ios_xe = 3.7.6s
cisco / ios_xe = 3.7.7s
cisco / ios_xe = 3.8.0s
cisco / ios_xe = 3.8.1s
cisco / ios_xe = 3.8.2s
cisco / ios_xe = 3.9.0as
cisco / ios_xe = 3.9.0s
cisco / ios_xe = 3.9.1as
cisco / ios_xe = 3.9.1s
cisco / ios_xe = 3.9.2s
cisco / ios_xe = 3.10.0s
cisco / ios_xe = 3.10.1s
cisco / ios_xe = 3.10.1xbs
cisco / ios_xe = 3.10.2s
cisco / ios_xe = 3.10.2ts
cisco / ios_xe = 3.10.3s
cisco / ios_xe = 3.10.4s
cisco / ios_xe = 3.10.5s
cisco / ios_xe = 3.10.6s
cisco / ios_xe = 3.10.7s
cisco / ios_xe = 3.10.8as
cisco / ios_xe = 3.10.8s
cisco / ios_xe = 3.10.9s
cisco / ios_xe = 3.10.10s
cisco / ios_xe = 3.11.0s
cisco / ios_xe = 3.11.1s
cisco / ios_xe = 3.11.2s
cisco / ios_xe = 3.11.3s
cisco / ios_xe = 3.11.4s
cisco / ios_xe = 3.12.0as
cisco / ios_xe = 3.12.0s
cisco / ios_xe = 3.12.1s
cisco / ios_xe = 3.12.2s
cisco / ios_xe = 3.12.3s
cisco / ios_xe = 3.12.4s
cisco / ios_xe = 3.13.0as
cisco / ios_xe = 3.13.0s
cisco / ios_xe = 3.13.1s
cisco / ios_xe = 3.13.2as
cisco / ios_xe = 3.13.2s
cisco / ios_xe = 3.13.3s
cisco / ios_xe = 3.13.4s
cisco / ios_xe = 3.13.5as
cisco / ios_xe = 3.13.5s
cisco / ios_xe = 3.13.6as
cisco / ios_xe = 3.13.6s
cisco / ios_xe = 3.13.7as
cisco / ios_xe = 3.13.7s
cisco / ios_xe = 3.13.8s
cisco / ios_xe = 3.13.9s
cisco / ios_xe = 3.13.10s
cisco / ios_xe = 3.14.0s
cisco / ios_xe = 3.14.1s
cisco / ios_xe = 3.14.2s
cisco / ios_xe = 3.14.3s
cisco / ios_xe = 3.14.4s
cisco / ios_xe = 3.15.0s
cisco / ios_xe = 3.15.1cs
cisco / ios_xe = 3.15.1s
cisco / ios_xe = 3.15.2s
cisco / ios_xe = 3.15.3s
cisco / ios_xe = 3.15.4s
cisco / ios_xe = 3.16.0cs
cisco / ios_xe = 3.16.0s
cisco / ios_xe = 3.16.1as
cisco / ios_xe = 3.16.1s
cisco / ios_xe = 3.16.2as
cisco / ios_xe = 3.16.2bs
cisco / ios_xe = 3.16.2s
cisco / ios_xe = 3.16.3as
cisco / ios_xe = 3.16.3s
cisco / ios_xe = 3.16.4as
cisco / ios_xe = 3.16.4bs
cisco / ios_xe = 3.16.4ds
cisco / ios_xe = 3.16.4s
cisco / ios_xe = 3.16.5s
cisco / ios_xe = 3.16.6bs
cisco / ios_xe = 3.16.6s
cisco / ios_xe = 3.16.7as
cisco / ios_xe = 3.16.7bs
cisco / ios_xe = 3.16.7s
cisco / ios_xe = 3.16.8s
cisco / ios_xe = 3.16.9s
cisco / ios_xe = 3.16.10s
cisco / ios_xe = 3.17.0s
cisco / ios_xe = 3.17.1as
cisco / ios_xe = 3.17.1s
cisco / ios_xe = 3.17.2s
cisco / ios_xe = 3.17.3s
cisco / ios_xe = 3.17.4s
cisco / ios_xe = 3.18.0as
cisco / ios_xe = 3.18.0s
cisco / ios_xe = 3.18.0sp
cisco / ios_xe = 3.18.1asp
cisco / ios_xe = 3.18.1bsp
cisco / ios_xe = 3.18.1csp
cisco / ios_xe = 3.18.1s
cisco / ios_xe = 3.18.1sp
cisco / ios_xe = 3.18.2asp
cisco / ios_xe = 3.18.2s
cisco / ios_xe = 3.18.2sp
cisco / ios_xe = 3.18.3asp
cisco / ios_xe = 3.18.3bsp
cisco / ios_xe = 3.18.3s
cisco / ios_xe = 3.18.3sp
cisco / ios_xe = 3.18.4s
cisco / ios_xe = 3.18.4sp
cisco / ios_xe = 3.18.5sp
cisco / ios_xe = 3.18.6sp
cisco / ios_xe = 3.18.7sp
cisco / ios_xe = 3.18.8asp
cisco / ios_xe = 3.18.9sp
cisco / ios_xe = 16.1.1
cisco / ios_xe = 16.1.2
cisco / ios_xe = 16.1.3
cisco / ios_xe = 16.2.1
cisco / ios_xe = 16.2.2
cisco / ios_xe = 16.3.1
cisco / ios_xe = 16.3.1a
cisco / ios_xe = 16.3.2
cisco / ios_xe = 16.3.3
cisco / ios_xe = 16.3.4
cisco / ios_xe = 16.3.5
cisco / ios_xe = 16.3.5b
cisco / ios_xe = 16.3.6
cisco / ios_xe = 16.3.7
cisco / ios_xe = 16.3.8
cisco / ios_xe = 16.3.9
cisco / ios_xe = 16.3.10
cisco / ios_xe = 16.3.11
cisco / ios_xe = 16.4.1
cisco / ios_xe = 16.4.2
cisco / ios_xe = 16.4.3
cisco / ios_xe = 16.5.1
cisco / ios_xe = 16.5.1a
cisco / ios_xe = 16.5.1b
cisco / ios_xe = 16.5.2
cisco / ios_xe = 16.5.3
cisco / ios_xe = 16.6.1
cisco / ios_xe = 16.6.2
cisco / ios_xe = 16.6.3
cisco / ios_xe = 16.6.4
cisco / ios_xe = 16.6.4a
cisco / ios_xe = 16.6.5
cisco / ios_xe = 16.6.5a
cisco / ios_xe = 16.6.6
cisco / ios_xe = 16.6.7
cisco / ios_xe = 16.6.8
cisco / ios_xe = 16.6.9
cisco / ios_xe = 16.6.10
cisco / ios_xe = 16.7.1
cisco / ios_xe = 16.7.1a
cisco / ios_xe = 16.7.1b
cisco / ios_xe = 16.7.2
cisco / ios_xe = 16.7.3
cisco / ios_xe = 16.7.4
cisco / ios_xe = 16.8.1
cisco / ios_xe = 16.8.1a
cisco / ios_xe = 16.8.1b
cisco / ios_xe = 16.8.1c
cisco / ios_xe = 16.8.1d
cisco / ios_xe = 16.8.1e
cisco / ios_xe = 16.8.1s
cisco / ios_xe = 16.8.2
cisco / ios_xe = 16.8.3
cisco / ios_xe = 16.9.1
cisco / ios_xe = 16.9.1a
cisco / ios_xe = 16.9.1b
cisco / ios_xe = 16.9.1s
cisco / ios_xe = 16.9.2
cisco / ios_xe = 16.9.3
cisco / ios_xe = 16.9.3a
cisco / ios_xe = 16.9.4
cisco / ios_xe = 16.9.5
cisco / ios_xe = 16.9.5f
cisco / ios_xe = 16.9.6
cisco / ios_xe = 16.9.7
cisco / ios_xe = 16.9.8
cisco / ios_xe = 16.10.1
cisco / ios_xe = 16.10.1a
cisco / ios_xe = 16.10.1b
cisco / ios_xe = 16.10.1c
cisco / ios_xe = 16.10.1d
cisco / ios_xe = 16.10.1e
cisco / ios_xe = 16.10.1f
cisco / ios_xe = 16.10.1g
cisco / ios_xe = 16.10.1s
cisco / ios_xe = 16.10.2
cisco / ios_xe = 16.10.3
cisco / ios_xe = 16.11.1
cisco / ios_xe = 16.11.1a
cisco / ios_xe = 16.11.1b
cisco / ios_xe = 16.11.1s
cisco / ios_xe = 16.11.2
cisco / ios_xe = 16.12.1
cisco / ios_xe = 16.12.1a
cisco / ios_xe = 16.12.1c
cisco / ios_xe = 16.12.1s
cisco / ios_xe = 16.12.1t
cisco / ios_xe = 16.12.1w
cisco / ios_xe = 16.12.1x
cisco / ios_xe = 16.12.1y
cisco / ios_xe = 16.12.1z1
cisco / ios_xe = 16.12.1z2
cisco / ios_xe = 16.12.2
cisco / ios_xe = 16.12.2a
cisco / ios_xe = 16.12.2s
cisco / ios_xe = 16.12.3
cisco / ios_xe = 16.12.3a
cisco / ios_xe = 16.12.3s
cisco / ios_xe = 16.12.4
cisco / ios_xe = 16.12.4a
cisco / ios_xe = 16.12.5
cisco / ios_xe = 16.12.5a
cisco / ios_xe = 16.12.5b
cisco / ios_xe = 16.12.6
cisco / ios_xe = 16.12.6a
cisco / ios_xe = 16.12.7
cisco / ios_xe = 16.12.8
cisco / ios_xe = 16.12.9
cisco / ios_xe = 16.12.10
cisco / ios_xe = 16.12.10a
cisco / ios_xe = 17.1.1
cisco / ios_xe = 17.1.1a
cisco / ios_xe = 17.1.1s
cisco / ios_xe = 17.1.1t
cisco / ios_xe = 17.1.3
cisco / ios_xe = 17.2.1
cisco / ios_xe = 17.2.1a
cisco / ios_xe = 17.2.1r
cisco / ios_xe = 17.2.1v
cisco / ios_xe = 17.2.2
cisco / ios_xe = 17.2.3
cisco / ios_xe = 17.3.1
cisco / ios_xe = 17.3.1a
cisco / ios_xe = 17.3.1w
cisco / ios_xe = 17.3.1x
cisco / ios_xe = 17.3.1z
cisco / ios_xe = 17.3.2
cisco / ios_xe = 17.3.2a
cisco / ios_xe = 17.3.3
cisco / ios_xe = 17.3.4
cisco / ios_xe = 17.3.4a
cisco / ios_xe = 17.3.4b
cisco / ios_xe = 17.3.4c
cisco / ios_xe = 17.3.5
cisco / ios_xe = 17.3.5a
cisco / ios_xe = 17.3.5b
cisco / ios_xe = 17.3.6
cisco / ios_xe = 17.3.7
cisco / ios_xe = 17.3.8
cisco / ios_xe = 17.3.8a
cisco / ios_xe = 17.4.1
cisco / ios_xe = 17.4.1a
cisco / ios_xe = 17.4.1b
cisco / ios_xe = 17.4.2
cisco / ios_xe = 17.4.2a
cisco / ios_xe = 17.5.1
cisco / ios_xe = 17.5.1a
cisco / ios_xe = 17.6.1
cisco / ios_xe = 17.6.1a
cisco / ios_xe = 17.6.1w
cisco / ios_xe = 17.6.1x
cisco / ios_xe = 17.6.1y
cisco / ios_xe = 17.6.1z
cisco / ios_xe = 17.6.1z1
cisco / ios_xe = 17.6.2
cisco / ios_xe = 17.6.3
cisco / ios_xe = 17.6.3a
cisco / ios_xe = 17.6.4
cisco / ios_xe = 17.6.5
cisco / ios_xe = 17.6.5a
cisco / ios_xe = 17.6.6
cisco / ios_xe = 17.6.6a
cisco / ios_xe = 17.7.1
cisco / ios_xe = 17.7.1a
cisco / ios_xe = 17.7.1b
cisco / ios_xe = 17.7.2
cisco / ios_xe = 17.8.1
cisco / ios_xe = 17.8.1a
cisco / ios_xe = 17.9.1
cisco / ios_xe = 17.9.1a
cisco / ios_xe = 17.9.1w
cisco / ios_xe = 17.9.1x
cisco / ios_xe = 17.9.1x1
cisco / ios_xe = 17.9.1y
cisco / ios_xe = 17.9.1y1
cisco / ios_xe = 17.9.2
cisco / ios_xe = 17.9.2a
cisco / ios_xe = 17.9.3
cisco / ios_xe = 17.9.3a
cisco / ios_xe = 17.9.4
cisco / ios_xe = 17.9.4a
cisco / ios_xe = 17.10.1
cisco / ios_xe = 17.10.1a
cisco / ios_xe = 17.10.1b
cisco / ios_xe = 17.11.1
cisco / ios_xe = 17.11.1a
cisco / ios_xe = 17.11.99sw
cisco / ios_xe = 17.12.1
cisco / ios_xe = 17.12.1a
cisco / ios_xe = 17.12.1w
cisco / ios_xe = 17.12.2
cisco / ios_xe = 17.12.2a

Frequently Asked Questions

A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.

CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.

A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.

Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.

Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.

SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.