How severe is CVE-2018-5743?

CVE-2018-5743 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2018-5743 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-5743?

CVE-2018-5743 primarily affects Isc Bind. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2018-5743?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-5743 published?

CVE-2018-5743 was published on 2019-10-09 and last updated on 2026-06-17.

CVE-2018-5743

CVE-2018-5743 is a high-severity vulnerability in Isc Bind with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 6% (93rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Isc Bind
Published: 2019-10-09
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2018-5743?: 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.
How severe is CVE-2018-5743?: CVE-2018-5743 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2018-5743 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (93rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-5743?: CVE-2018-5743 primarily affects Isc Bind. In total, 35 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2018-5743?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-5743 published?: CVE-2018-5743 was published on 2019-10-09 and last updated on 2026-06-17.

References

Affected products (35)

cpe:2.3:a:f5:big-ip_local_traffic_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_local_traffic_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_application_acceleration_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_application_acceleration_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_advanced_firewall_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_advanced_firewall_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_analytics:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_analytics:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_access_policy_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_access_policy_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_application_security_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_application_security_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_edge_gateway:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_edge_gateway:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_fraud_protection_service:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_fraud_protection_service:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_global_traffic_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_global_traffic_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_link_controller:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_link_controller:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_webaccelerator:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_webaccelerator:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_policy_enforcement_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_policy_enforcement_manager:15.0.0:*:*:*:*:*:*:*
cpe:2.3:a:isc:bind:*:*:*:*:*:*:*:*
cpe:2.3:a:isc:bind:9.9.3:s1:*:*:supported_preview:*:*:*
cpe:2.3:a:isc:bind:9.10.8:p1:*:*:*:*:*:*
cpe:2.3:a:isc:bind:9.11.5:s3:*:*:supported_preview:*:*:*
cpe:2.3:a:isc:bind:9.11.5:s5:*:*:supported_preview:*:*:*
cpe:2.3:a:isc:bind:9.14.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:enterprise_manager:3.1.1:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-iq_centralized_management:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:iworkflow:2.3.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_domain_name_system:*:*:*:*:*:*:*:*
cpe:2.3:a:f5:big-ip_domain_name_system:15.0.0:*:*:*:*:*:*:*

More vulnerabilities in Isc Bind

CVE-2008-0122 — Critical (CVSS 10.0): Off-by-one error in the inet_network function in libbind in ISC BIND 9.4.2 and earlier, as used in libc in FreeBSD 6.2…
CVE-2001-0011 — Critical (CVSS 10.0): Buffer overflow in nslookupComplain function in BIND 4 allows remote attackers to gain root privileges.
CVE-2001-0013 — Critical (CVSS 10.0): Format string vulnerability in nslookupComplain function in BIND 4 allows remote attackers to gain root privileges.
CVE-2001-0010 — Critical (CVSS 10.0): Buffer overflow in transaction signature (TSIG) handling code in BIND 8 allows remote attackers to gain root privileges.
CVE-2000-1029 — Critical (CVSS 10.0): Buffer overflow in host command allows a remote attacker to execute arbitrary commands via a long response to an AXFR…
CVE-1999-0837 — Critical (CVSS 10.0): Denial of service in BIND by improperly closing TCP sessions via so_linger.

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