--- title: "CVE-2018-18584\n | Ubuntu" description: Ubuntu is an open source software operating system that runs from the desktop, to the cloud, to all your internet connected things. url: https://ubuntu.com/security/CVE-2018-18584?format=md keywords: index, follow --- # CVE-2018-18584 Publication date 22 October 2018 Last updated 25 August 2025 --- Ubuntu priority **Medium** [Why this priority?](https://ubuntu.com/security/cves/about#priority ) ## Cvss 3 Severity Score **6.5 · Medium** [Score breakdown](https://ubuntu.com/security/CVE-2018-18584?format=md#impact-score) Toggle side navigation ## Description In mspack/cab.h in libmspack before 0.8alpha and cabextract before 1.8, the CAB block input buffer is one byte too small for the maximal Quantum block, leading to an out-of-bounds write. ### From the Ubuntu Security Team It was discovered that cabextract incorrectly handled certain malformed CAB files. A remote attacker could use this issue to cause cabextract to crash, resulting in a denial of service. [Read the notes from the security team](https://ubuntu.com/security/CVE-2018-18584?format=md#notes) ## Status Show unmaintained releases | Package | Ubuntu Release | Status | | --- | --- | --- | | cabextract | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 19.10 eoan | Not affected | | 19.04 disco | Not affected | | 18.10 cosmic | Not affected | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Fixed 1.4-4ubuntu0.1~esm1 Ubuntu Pro | | clamav | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 19.10 eoan | Not affected | | 19.04 disco | Not affected | | 18.10 cosmic | Not affected | | 18.04 LTS bionic | Not affected | | 16.04 LTS xenial | Not affected | | 14.04 LTS trusty | Fixed 0.100.2+dfsg-1ubuntu0.14.04.2 | | libmspack | 22.04 LTS jammy | Not affected | | 21.10 impish | Not affected | | 21.04 hirsute | Not affected | | 20.10 groovy | Not affected | | 20.04 LTS focal | Not affected | | 19.10 eoan | Not affected | | 19.04 disco | Not affected | | 18.10 cosmic | Fixed 0.7-1ubuntu0.1 | | 18.04 LTS bionic | Fixed 0.6-3ubuntu0.2 | | 16.04 LTS xenial | Fixed 0.5-1ubuntu0.16.04.3 | | 14.04 LTS trusty | Fixed 0.4-1ubuntu0.1~esm1 Ubuntu Pro | --- * [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) * [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses) * [Patch details](https://ubuntu.com/security/CVE-2018-18584?format=md#patch-details) ### Get expanded security coverage with Ubuntu Pro Reduce your average CVE exposure time from 98 days to 1 day with expanded CVE patching, ten-years security maintenance and optional support for the full stack of open-source applications. Free for personal use. [Get Ubuntu Pro](https://ubuntu.com/pro) [30-day free trial](https://ubuntu.com/pro/free-trial) ## Notes --- ### [alexmurray](https://launchpad.net/~alexmurray) We released clamav 0.100.2+dfsg-1ubuntu0.1X.04.2 for precise/esm and trusty, but subsequently were notified the bundled libmspack is not actually vulnerable in this case, as the version of libmspack provided had increased the CAB\_BLOCKMAX macro to 65535, meaning that CAB\_INPUTMAX is now 71679, which is impossible to encode in the 16-bit cfdata\_CompressedSize field of a single block. ### Patch details For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security) | Package | Patch details | | --- | --- | | libmspack | * Upstream: [40ef1b4](https://github.com/kyz/libmspack/commit/40ef1b4093d77ad3a5cfcee1f5cb6108b3a3bcc2) | ## Severity score breakdown CVSS version: CVSS v3.0 **Base score** 6.5 · Medium * Base metrics | Parameter | Value | | --- | --- | | Attack vector | Network | | Attack complexity | Low | | Privileges required | None | | User interaction | Required | | Scope | Unchanged | | Confidentiality impact | None | | Integrity impact | None | | Availability impact | High | * Scores | Parameter | Value | | --- | --- | | Base score | 6.5 · Medium | | Exploitability score | - | | Impact score | - | **Vector:** CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H ## References * [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-18584) * [NVD](https://nvd.nist.gov/vuln/detail/CVE-2018-18584) * [Launchpad](https://launchpad.net/bugs/cve/CVE-2018-18584) * [Debian](https://security-tracker.debian.org/tracker/CVE-2018-18584) ### Related Ubuntu Security Notices (USN) + [USN-3814-1](https://usn.ubuntu.com/USN-3814-1) + libmspack vulnerabilities + 12 November 2018 + [USN-3814-2](https://usn.ubuntu.com/USN-3814-2) + ClamAV vulnerabilities + 13 November 2018 + [USN-3814-3](https://usn.ubuntu.com/USN-3814-3) + ClamAV vulnerabilities + 13 November 2018 ### Other references * * *