How severe is CVE-2018-0159?

CVE-2018-0159 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2018-0159?

Affected package information for CVE-2018-0159 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2018-0159?

No fixed version has been published for CVE-2018-0159 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2018-0159 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2018-0159, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2018-0159?

CVE-2018-0159 has an EPSS (Exploit Prediction Scoring System) score of 7.0%, placing it in the 92th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2018-0159 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2018-0159 (Cisco IOS and XE Software Internet Key Exchange Version 1 Denial-of-Service Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-03-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-03-17. The required action was: Apply updates per vendor instructions. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2018-0159?

CVE-2018-0159 is classified as Improper Input Validation (CWE-20). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2018-0159?

CVE-2018-0159 affects cisco ios (1 version, e.g. 15.3\(3\)s); cisco ios xe (1 version, e.g. 15.3\(3\)s). Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2018-0159 published, and has it been updated?

CVE-2018-0159 was published on March 28, 2018 and was last updated on January 14, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2018-0159: IOS Improper Input Validation (High 7.5)

EPSS Exploitation Probability

via FIRST.org ↗

7.0%probability of exploitation in next 30 days

Lower Risk92th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

A vulnerability in the implementation of Internet Key Exchange Version 1 (IKEv1) functionality in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific IKEv1 packets. An attacker could exploit this vulnerability by sending crafted IKEv1 packets to an affected device during an IKE negotiation. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCuj73916.

Affected Products

2 products · 2 configurations

OS

ioscisco

1 version

15.3\(3\)s

OS

ios xecisco

1 version

15.3\(3\)s

Frequently Asked Questions

A vulnerability in the implementation of Internet Key Exchange Version 1 (IKEv1) functionality in Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific IKEv1 packets. An attacker could exploit this vulnerability by sending crafted IKEv1 packets to an affected device during an IKE negotiation. A successful exploit could allow the attacker to cause an affected device to reload, resulting in a DoS condition. Cis

O3 Security · Impact-Aware SCA

Is CVE-2018-0159 in your stack?

O3 detects CVE-2018-0159 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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