CVE-2018-5743
Limiting simultaneous TCP clients was ineffective
- Published
- Updated
- Reserved
- Assigned by
- isc
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| iscCNA (assigner) | 3.0 | High7.5 | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 6.4% · top 6.3% of all CVEs (4 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
- By exploiting the failure to limit simultaneous TCP connections, an attacker can deliberately exhaust the pool of file descriptors available to named, potentially affecting network connections and the management of files such as log files or zone journal files. In cases where the named process is not limited by OS-enforced per-process limits, this could additionally potentially lead to exhaustion of all available free file descriptors on that system.
- CWE-770 (opens in a new tab)All about CWE-770 and its CVEs
Affected products
- 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.
What to do
Solution: Upgrade to a version of BIND containing a fix for the ineffective limits. + BIND 9.11.6-P1 + BIND 9.12.4-P1 + BIND 9.14.1 BIND Supported Preview Edition is a special feature preview branch of BIND provided to eligible ISC support customers. + BIND 9.11.5-S6 + BIND 9.11.6-S1
References (3)
- https://kb.isc.org/docs/cve-2018-5743 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://www.synology.com/security/advisory/Synology_SA_19_20 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://support.f5.com/csp/article/K74009656?utm_source=f5support&%3Butm_medium=RSS (opens in a new tab)x_refsource_CONFIRMx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2018-5743)Record last updated .