CVE-2018-18585: chmd_read_headers in mspack/chmd.c in libmspack before 0.8alpha accepts a filename that has '\0' as its first

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MEDIUM 4.3WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2018-18585 is a medium-severity flaw (CVSS 4.3) affecting libmspack, debian linux, enterprise linux desktop. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

chmd_read_headers in mspack/chmd.c in libmspack before 0.8alpha accepts a filename that has '\0' as its first or second character (such as the "/\0" name).

Why this priority

Public exploit reference
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	3.0% (top 13%)
CISA exploited list	No
Weakness	CWE-476
Published	2018-10-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · kyzer · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2018-10-23 02:29 UTCPublished CVE record published
2026-06-17 01:47 UTCUpdated Record last modified

kyzer libmspack DOWNGRADE

Affected: 0.3 alpha · 0.4 alpha · 0.5 alpha · 0.6 alpha · 0.7 alpha

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.3

1. Check installed version

apt-cache policy libmspack || rpm -q libmspack || libmspack --version

2. No fixed release: DOWNGRADE to a release before 0.3 (Debian / Ubuntu)

apt-cache madison libmspack sudo apt install libmspack=<VERSION_BEFORE_0.3> sudo apt-mark hold libmspack

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list libmspack sudo dnf downgrade libmspack-<VERSION_BEFORE_0.3> sudo dnf versionlock add libmspack

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux desktop MITIGATE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux server MITIGATE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat enterprise linux workstation MITIGATE

Affected: 7.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04 · 16.04 · 18.04 · 18.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2018-18585?

libmspack: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation; enterprise linux desktop: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2018-18585 being exploited?

CVE-2018-18585 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2018-18585 affect?

CVE-2018-18585 affects libmspack, debian linux, enterprise linux desktop. Severity is medium (CVSS 4.3). chmd_read_headers in mspack/chmd.c in libmspack before 0.8alpha accepts a filename that has '\0' as its first or second character (such as the "/\0" name).

How urgent is CVE-2018-18585?

Priority 47/100. Public exploit reference; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities

Related CVEs

CVE-2019-1010305 MEDIUM 5.5 DOWNGRADE MITIGATE libmspack 0.9.1alpha is affected by: Buffer Overflow
CVE-2018-18586 MEDIUM 5.3 DOWNGRADE chmextract.c in the chmextract sample program, as distributed with libmspack before 0.8alpha, does not protect
CVE-2018-18584 MEDIUM 6.5 UPGRADE DOWNGRADE In mspack/cab.h in libmspack before 0.8alpha and cabextract before 1.8, the CAB block input buffer is one byte
CVE-2018-14682 HIGH 8.8 DOWNGRADE UPGRADE An issue was discovered in mspack/chmd.c in libmspack before 0.7alpha
CVE-2018-14681 HIGH 8.8 DOWNGRADE UPGRADE An issue was discovered in kwajd_read_headers in mspack/kwajd.c in libmspack before 0.7alpha

References

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