CVE-2018-0155
Cisco Ios 3.6\(2\)e
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2018-0155 is a high-severity Improper Handling of Exceptional Conditions (CWE-755) vulnerability in Cisco Ios. Its CVSS base score is 8.6 (High).
Operationally, ranked in the top 5% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A vulnerability exists in the Bidirectional Forwarding Detection (BFD) offload implementation of Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches. The flaw stems from insufficient error handling when processing BFD packets that contain an incomplete BFD header, which can cause the iosd process to crash. Affected hardware includes the Catalyst 4500 Supervisor Engine 6-E (K5), 6L-E (K10), 7-E (K10), 7L-E (K10), 8-E (K10), 8L-E (K10), 9-E (K10), Catalyst 4500-X Series Switches (K10), Catalyst 4900M Switch (K5), and Catalyst 4948E Ethernet Switch (K5), as tracked under Cisco Bug ID CSCvc40729.
An unauthenticated remote attacker can exploit the issue by sending a crafted BFD message to or across an affected switch. Successful exploitation results in a denial-of-service condition through a system reload. The vulnerability carries a CVSS 3.1 base score of 8.6, reflecting network attack vector, low attack complexity, and no required privileges or user interaction, with high impact on availability and scope change.
The Cisco Security Advisory cisco-sa-20180328-bfd, along with related notices from SecurityFocus, SecurityTracker, and ICS-CERT, provides official details on the issue and recommended mitigation steps. No information on observed in-the-wild exploitation is included in the available references.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2018-0978
Vulnerability Data
A vulnerability in the Bidirectional Forwarding Detection (BFD) offload implementation of Cisco Catalyst 4500 Series Switches and Cisco Catalyst 4500-X Series Switches could allow an unauthenticated, remote attacker to cause a crash of the iosd process, causing a denial of…
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service (DoS) condition. The vulnerability is due to insufficient error handling when the BFD header in a BFD packet is incomplete. An attacker could exploit this vulnerability by sending a crafted BFD message to or across an affected switch. A successful exploit could allow the attacker to trigger a reload of the system. This vulnerability affects Catalyst 4500 Supervisor Engine 6-E (K5), Catalyst 4500 Supervisor Engine 6L-E (K10), Catalyst 4500 Supervisor Engine 7-E (K10), Catalyst 4500 Supervisor Engine 7L-E (K10), Catalyst 4500E Supervisor Engine 8-E (K10), Catalyst 4500E Supervisor Engine 8L-E (K10), Catalyst 4500E Supervisor Engine 9-E (K10), Catalyst 4500-X Series Switches (K10), Catalyst 4900M Switch (K5), Catalyst 4948E Ethernet Switch (K5). Cisco Bug IDs: CSCvc40729.
- CWE(s)
- KEV Date Added
- 03 March 2022
Related Threats
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Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Provides defined handling (alert and additional actions) for the exceptional condition of audit logging failure.
Supplies a concrete handling action (safe mode) for exceptional conditions, mitigating risks from improper or absent handling that could allow continued attacks.
By preparing users for contingency scenarios, the control promotes proper handling of exceptional conditions instead of default or unsafe behaviors.
An updated contingency plan defines current actions for exceptional conditions, reducing the window for attackers to exploit improper handling leading to system failure.
Procedures ensure proper handling of exceptional conditions to support effective incident response.
Incident response testing confirms proper handling of exceptional conditions to limit exploit impact.
Gives users guidance on incident handling, reducing improper handling of exceptional conditions that could stem from exploited weaknesses.
Enforces structured response to exceptional conditions so the system cannot remain in an unsafe state.
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.
Documented operating procedures may specify exception handling but do not guarantee implementation.
Logging captures unhandled exceptions, aiding detection but not preventing the weakness.
Monitoring can surface unhandled exceptions but does not enforce proper handling.
Secure SDLC mandates exception-handling requirements and testing that directly prevent improper handling of exceptional conditions.
A.8.26 explicitly lists resilience against malicious attacks including SQL injections, input validation, error message handling, and several integrity/authorization requirements that address exceptional conditions in a minority of cases, but most CWE-755 instances (e.g. unhandled nulls, resource errors, unexpected states) fall outside its named topics.
A.8.27 mandates security-by-design principles (fail securely, least privilege, defense-in-depth, distrust external input, assume-breach) plus design reviews that can catch and stop many but not all mishandlings of exceptional conditions before they reach production code; a bounded remainder (e.g. subtle runtime error paths, library-level faults, or post-review regressions) can still be present and exploitable.
Hardening callouts derived
DISA STIG baselines are authored against specific weaknesses. Where this CVE cites a broad weakness class, the mapping is not asserted at that abstraction (owner ruling, 2026-09-25: grade only at Base and below), so no rule is shown here rather than a rule shown against the wrong grain.