What’s Vulnerable › Vulnerabilities

CVE-2018-5743: Limiting simultaneous TCP clients was ineffective

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2019-10-09 · updated 2026-06-17
• Weakness: CWE-770

Description

By design, BIND is intended to limit the number of TCP clients that can be connected at any given time. The number of allowed connections is a tunable parameter which, if unset, defaults to a conservative value for most servers. Unfortunately, the code which was intended to limit the number of simultaneous connections contained an error which could be exploited to grow the number of simultaneous connections beyond this limit. Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.6, 9.12.0 -> 9.12.4, 9.14.0. BIND 9 Supported Preview Edition versions 9.9.3-S1 -> 9.11.5-S3, and 9.11.5-S5. Versions 9.13.0 -> 9.13.7 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5743.

Affected products

• F5 BIG-IP APM: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.1.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• BIG-IP: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.1.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Analytics: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Networks, Inc. BIG-IP (AAM): from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• BIG-IP ASM: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.1; 15.0.0
• F5 BIG-IP DNS: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.1.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Edge Gateway: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Fraud Protection Service: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Global Traffic Manager: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Link Controller: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 BIG-IP (LTM): from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.0.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Networks, Inc. BIG-IP (PEM): from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.1.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 Big-Ip Webaccelerator: from 11.5.2 through 11.6.5; from 12.1.0 through 12.1.4; from 13.1.0 through 13.1.1; from 14.0.0 through 14.1.0; 15.0.0
• F5 BIG-IQ: from 5.0.0 through 5.4.0; from 6.0.0 through 6.1.0
• F5 Networks, Inc. Enterprise Manager: 3.1.1
• F5 Networks, Inc. iWorkflow: 2.3.0
• ISC BIND: from 9.9.0 through 9.10.8; from 9.11.0 through 9.11.6; from 9.12.0 through 9.12.4; from 9.13.0 through 9.13.7; 9.9.3-s1, 9.10.8-p1, 9.11.5-s3, 9.11.5-s5, 9.14.0

References

• https://kb.isc.org/docs/cve-2018-5743
• https://support.f5.com/csp/article/K74009656?utm_source=f5support&amp%3Butm_medium=RSS
• https://www.synology.com/security/advisory/Synology_SA_19_20
• https://kb.isc.org/docs/cve-2018-5743
• https://support.f5.com/csp/article/K74009656?utm_source=f5support&amp%3Butm_medium=RSS
• https://www.synology.com/security/advisory/Synology_SA_19_20

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