CVE-2023-20236: Cisco IOS XR Software · Improper Verification of Cryptographic Signature
Affects Cisco IOS XR SoftwareSource CVE Database V5
Not known to be exploited · CVSS 6.7 Medium.
Data as of 26 Oct 2026, 06:26 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 0% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 13 Sep 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Cisco Cisco IOS XR Software | Affected
| Fixed in– |
AI-suggested
Organizations should prioritize the following mitigations: 1) Monitor Cisco advisories and apply official patches or updates for IOS XR versions as soon as they become available to address this vulnerability. 2) Restrict local administrative access to IOS XR devices using strong authentication mechanisms and network segmentation to minimize the risk of unauthorized local access. 3) Implement strict access controls and audit logging on devices to detect and respond to suspicious boot parameter changes or unauthorized configuration modifications. 4) Employ network monitoring tools to detect anomalous device behavior indicative of firmware tampering or unauthorized reboots. 5) Conduct regular security reviews and penetration testing focused on local access controls and boot process integrity. 6) Where possible, leverage hardware-based security features such as secure boot and trusted platform modules to enforce image verification. 7) Educate network administrators on the risks of local privilege misuse and enforce the principle of least privilege for device management.
Description
CVE-2023-20236 is a vulnerability in Cisco IOS XR software's iPXE boot function that allows an authenticated local attacker to bypass cryptographic signature verification and install an unverified software image. Exploitation requires local access with high privileges and no user interaction. Successful exploitation can compromise confidentiality, integrity, and availability by booting malicious firmware. The vulnerability affects numerous IOS XR versions widely used in network infrastructure. While no known exploits are reported in the wild, the medium CVSS score reflects the significant impact but limited attack vector. European organizations relying on Cisco IOS XR for critical routing and network functions are at risk, especially in countries with high Cisco market penetration and critical telecom infrastructure. Mitigation involves applying vendor patches once available, restricting local access, and monitoring boot configurations. Countries like Germany, France, UK, Italy, and the Netherlands are most likely affected due to their extensive Cisco deployments and strategic network importance.