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

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.

Published: 2019-10-09 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-5743 is rated High Risk (68.4/100): CVSS High severity, with high exploitation likelihood (EPSS 11.56%, 95th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. EPSS rose +5.87% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-5743

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 5.69% 11.56% +5.87%
2 2026-03-03 1.77% 5.69% +3.93%
3 2025-11-21 — 1.77% —

Full EPSS history (14 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-5743

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2018-5743

OS Trackers for CVE-2018-5743

vendor priority summary link
alpine high CVE-2018-5743: 1 source package rows (bind); 10 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 10, open 0. https://security.alpinelinux.org/vuln/CVE-2018-5743
debian not yet assigned CVE-2018-5743 not yet assigned priority: Debian including 1 source packages (bind9), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2018-5743
redhat high — https://access.redhat.com/security/cve/CVE-2018-5743
suse high — https://www.suse.com/security/cve/CVE-2018-5743/
ubuntu medium CVE-2018-5743 medium priority: Ubuntu including 1 source packages (bind9), 6 status rows across 6 suites (bionic, cosmic, disco, trusty, upstream, xenial): released 5, needs-triage 1. https://ubuntu.com/security/CVE-2018-5743

Affected software / configurations for CVE-2018-5743

Vendor Product Version Raw CPE
f5 big-ip_local_traffic_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_local_traffic_manager 15.0.0 cpe:2.3:a:f5:big-ip_local_traffic_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_acceleration_manager 15.0.0 cpe:2.3:a:f5:big-ip_application_acceleration_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 13.1.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
f5 big-ip_advanced_firewall_manager 15.0.0 cpe:2.3:a:f5:big-ip_advanced_firewall_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_analytics >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_analytics >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_analytics >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_analytics >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
f5 big-ip_analytics 15.0.0 cpe:2.3:a:f5:big-ip_analytics:15.0.0:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager >= 13.1.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
f5 big-ip_access_policy_manager 15.0.0 cpe:2.3:a:f5:big-ip_access_policy_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager >= 14.0.0, <= 14.1.1 cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
f5 big-ip_application_security_manager 15.0.0 cpe:2.3:a:f5:big-ip_application_security_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_edge_gateway >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
f5 big-ip_edge_gateway >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
f5 big-ip_edge_gateway >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
f5 big-ip_edge_gateway >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
f5 big-ip_edge_gateway 15.0.0 cpe:2.3:a:f5:big-ip_edge_gateway:15.0.0:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
f5 big-ip_fraud_protection_service 15.0.0 cpe:2.3:a:f5:big-ip_fraud_protection_service:15.0.0:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
f5 big-ip_global_traffic_manager 15.0.0 cpe:2.3:a:f5:big-ip_global_traffic_manager:15.0.0:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 13.0.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_link_controller >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
f5 big-ip_link_controller 15.0.0 cpe:2.3:a:f5:big-ip_link_controller:15.0.0:*:*:*:*:*:*:*
f5 big-ip_webaccelerator >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
f5 big-ip_webaccelerator >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
f5 big-ip_webaccelerator >= 13.1.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
f5 big-ip_webaccelerator >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
f5 big-ip_webaccelerator 15.0.0 cpe:2.3:a:f5:big-ip_webaccelerator:15.0.0:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 13.1.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
f5 big-ip_policy_enforcement_manager 15.0.0 cpe:2.3:a:f5:big-ip_policy_enforcement_manager:15.0.0:*:*:*:*:*:*:*
isc bind >= 9.9.0, <= 9.10.8 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.11.0, <= 9.11.6 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.12.0, <= 9.12.4 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind >= 9.13.0, <= 9.13.7 cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
isc bind 9.9.3 cpe:2.3:a:isc:bind:9.9.3:s1:*:*:supported_preview:*:*:*
isc bind 9.10.8 cpe:2.3:a:isc:bind:9.10.8:p1:*:*:*:*:*:*
isc bind 9.11.5 cpe:2.3:a:isc:bind:9.11.5:s3:*:*:supported_preview:*:*:*
isc bind 9.11.5 cpe:2.3:a:isc:bind:9.11.5:s5:*:*:supported_preview:*:*:*
isc bind 9.14.0 cpe:2.3:a:isc:bind:9.14.0:*:*:*:*:*:*:*
f5 enterprise_manager 3.1.1 cpe:2.3:a:f5:enterprise_manager:3.1.1:*:*:*:*:*:*:*
f5 big-iq_centralized_management >= 5.0.0, <= 5.4.0 cpe:2.3:a:f5:big-iq_centralized_management:*:*:*:*:*:*:*:*
f5 big-iq_centralized_management >= 6.0.0, <= 6.1.0 cpe:2.3:a:f5:big-iq_centralized_management:*:*:*:*:*:*:*:*
f5 iworkflow 2.3.0 cpe:2.3:a:f5:iworkflow:2.3.0:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 11.5.2, <= 11.6.5 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 12.1.0, <= 12.1.4 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 13.1.0, <= 13.1.1 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system >= 14.0.0, <= 14.1.0 cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
f5 big-ip_domain_name_system 15.0.0 cpe:2.3:a:f5:big-ip_domain_name_system:15.0.0:*:*:*:*:*:*:*

References for CVE-2018-5743

cvelogic Threat Intelligence