Limiting simultaneous TCP clients was ineffective

Published 7 y ago 2019-10-09 · modified 4 mo ago 2026-06-17 · JSON

CVSS

7.5

v3.0 · CNA

CISA KEV

not known exploited

EPSS

6.4%

percentile 94%

Public exploits

none known

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.

Exploit prediction (EPSS)

6.43% probability of exploitation in the next 30 days, higher than 94% of all scored CVEs.

CVSS scores

Assigned by	Version	Score	Vector
CNA	3.0	7.5	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`
NVD	3.1	7.5	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`
CNA	3.0	7.5	`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`
NVD	2.0	4.3	`AV:N/AC:M/Au:N/C:N/I:N/A:P`

Affected products

ISC BIND 9

Classification

Weakness

CWE-770 Allocation of Resources Without Limits or Throttling

References

kb.isc.org /docs/cve-2018-5743 · x_refsource_CONFIRM, x_transferred
synology.com /security/advisory/Synology_SA_19_20 · x_refsource_CONFIRM, x_transferred
support.f5.com /csp/article/K74009656?utm_source=f5support&amp%3Butm_medium=RSS · x_refsource_CONFIRM, x_transferred

Sources

CVE List: CVE-2018-5743
NVD: CVE-2018-5743

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