CVE-2018-15399

MEDIUMNVD 6.86.8—
EchelonGraph scoreMEDIUM confidence

Score 6.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-13. NVD baseline CVSS 6.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
6.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 6.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A vulnerability in the TCP syslog module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust the 1550-byte buffers on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to a missing boundary check in an internal function. An attacker could exploit this vulnerability by establishing a man-in-the-middle position between an affected device and its configured TCP syslog server and then maliciously modifying the TCP header in segments that are sent from the syslog server to the affected device. A successful exploit could allow the attacker to exhaust buffer on the affected device and cause all TCP-based features to stop functioning, resulting in a DoS condition. The affected TCP-based features include AnyConnect SSL VPN, clientless SSL VPN, and management connections such as Secure Shell (SSH), Telnet, and HTTPS.

CVSS v3
6.8
EG Score
6.8(medium)
EG Risk
31(Track)
EG Risk 31/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity68% × 45%
Exploitation2% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
76.8%
KEV
Not listed

Published

October 5, 2018

Last Modified

November 21, 2024

References (4)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 01:33 UTCEG score recompute
  2. 2026-07-22 22:13 UTCEG score recompute
  3. 2026-07-22 14:04 UTCEPSS rescore
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  61. 2026-05-28 02:26 UTCGHSA enrichment
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Frequently asked(5)

What is CVE-2018-15399?
CVE-2018-15399 is a medium vulnerability published on October 5, 2018. A vulnerability in the TCP syslog module of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust the 1550-byte buffers on an affected device, resulting in a denial of service (DoS) condition.…
When was CVE-2018-15399 disclosed?
CVE-2018-15399 was first published in the National Vulnerability Database on October 5, 2018, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2018-15399 actively exploited?
CVE-2018-15399 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 76.8% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2018-15399?
CVE-2018-15399 has a CVSS v3 base score of 6.8 (NVD).
How do I remediate CVE-2018-15399?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2018-15399, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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