# CVE-2018-5738: Some versions of BIND can improperly permit recursive query service to unauthorized clients

> Attackers can perform unauthorized recursive queries on BIND servers due to a regression in default configuration handling, bypassing intended access restrictions.

- **Severity:** Medium 5.3 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jan 2019
- **Updated:** 16 Sep 2024
- **Also known as:** ALPINE-CVE-2018-5738, DEBIAN-CVE-2018-5738, GHSA-cg2m-4gq8-j388, UBUNTU-CVE-2018-5738, USN-3683-1

## What is CVE-2018-5738?

CVE-2018-5738 is a medium-severity authentication bypass vulnerability in Canonical Ubuntu Linux, published on 16 Jan 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Change #4777 (introduced in October 2017) introduced an unforeseen issue in releases which were issued after that date, affecting which clients are permitted to make recursive queries to a BIND nameserver. The intended (and documented) behavior is that if an operator has not specified a value for the "allow-recursion" setting, it SHOULD default to one of the following: none, if "recursion no;" is set in named.conf; a value inherited from the "allow-query-cache" or "allow-query" settings IF "recursion yes;" (the default for that setting) AND match lists are explicitly set for "allow-query-cache" or "allow-query" (see the BIND9 Administrative Reference Manual section 6.2 for more details); or the intended default of "allow-recursion {localhost; localnets;};" if "recursion yes;" is in effect and no values are explicitly set for "allow-query-cache" or "allow-query". However, because of the regression introduced by change #4777, it is possible when "recursion yes;" is in effect and no match list values are provided for "allow-query-cache" or "allow-query" for the setting of "allow-recursion" to inherit a setting of all hosts from the "allow-query" setting default, improperly permitting recursion to all clients. Affects BIND 9.9.12, 9.10.7, 9.11.3, 9.12.0->9.12.1-P2, the development release 9.13.0, and also releases 9.9.12-S1, 9.10.7-S1, 9.11.3-S1, and 9.11.3-S2 from BIND 9 Supported Preview Edition.

Weakness: CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2018-5738?

It affects 2 products.


Products: Canonical Ubuntu Linux, Isc Bind.

## How do I fix CVE-2018-5738?

Apply the vendor's patch.

## Is CVE-2018-5738 being exploited?

There is no known exploitation of CVE-2018-5738 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-5738 and fix it if it is affected.

What it is: CVE-2018-5738 is a medium-severity authentication bypass vulnerability in Canonical Ubuntu Linux, published on 16 Jan 2019. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2018-5738 in the wild and no public exploit code.

Affected product: Canonical Ubuntu Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2018-5738/ (Markdown: https://insights.sbomify.com/CVE-2018-5738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-5738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-5738
- OSV: https://osv.dev/vulnerability/CVE-2018-5738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2018-5738/
Summaries are generated and may contain mistakes; the official description above is the record.