Impact: Important Public Date: 2019-04-24 Bugzilla: 1702541: CVE-2018-5743 bind: Limiting simultaneous TCP clients is ineffective A flaw was found in the way bind implemented tunable which limited simultaneous TCP client connections. A remote attacker could use this flaw to 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.
Find out more about CVE-2018-5743 from the MITRE CVE dictionary dictionary and NIST NVD.
This bind flaw can be exploited by a remote attacker (AV:N) by opening large number of simultaneous TCP client connections with the server. No special exploit code is required apart from the ability to open large number of TCP connections simultaneously either from one attacker machine or via some distributed attacker network (AC:L and PR:L). No user interaction is required from the server side (UI:N). The attacker can cause denial of service (A:H) by exhausting the file descriptor pool which named has access to. Also in cases where named process is not limited by OS-enforced per-process limits, this could cause exhaustion of available free file descriptors on the system running the named server causing denial of service for other processes running on that machine (S:C).
NOTE: The following CVSS v3 metrics and score provided are preliminary and subject to review.
| CVSS3 Base Score | 8.6 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| Attack Vector | Network |
| Attack Complexity | Low |
| Privileges Required | None |
| User Interaction | None |
| Scope | Changed |
| Confidentiality | None |
| Integrity Impact | None |
| Availability Impact | High |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 7 | bind | Affected |
| Red Hat Enterprise Linux 6 | bind | Affected |
| Red Hat Enterprise Linux 5 | bind97 | Will not fix |
| Red Hat Enterprise Linux 5 | bind | Will not fix |
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