PatchTheCVECVE-2023-42521: Certain WithSecure products allow a remote crash of a scanning engine via processing of a compressed file
49
This month
HIGH 7.5REMOTEWATCHLISTDOWNGRADEDOWNGRADEDOWNGRADE
CVE-2023-42521 is a high-severity flaw (CVSS 7.5) affecting client security, elements endpoint protection, email and server security. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Certain WithSecure products allow a remote crash of a scanning engine via processing of a compressed file. This affects WithSecure Client Security 15, WithSecure Server Security 15, WithSecure Email and Server Security 15, WithSecure Elements Endpoint Protection 17 and later, WithSecure Client Security for Mac 15, WithSecure Elements Endpoint Protection for Mac 17 and later, Linux Security 64 12.0 , Linux Protection 12.0, and WithSecure Atlant (f
Why this priority
- High severity
- Remotely exploitable, no login, no user action
- On your watchlist
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 7.5 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.6% (top 51%) |
| CISA exploited list | No |
| Weakness | CWE-400 |
| Published | 2023-09-18 |
| Last modified | 2026-06-17 |
Publisher (CNA): MITRE · Vendor: withsecure
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
withsecure client security DOWNGRADE
Affected: 15
Fixed in: no fixed release known
Safe to downgrade to: a release before 15
1. Check installed version
apt-cache policy client-security || rpm -q client-security || client-security --version
2. No fixed release: DOWNGRADE to a release before 15 (Debian / Ubuntu)
apt-cache madison client-security
sudo apt install client-security=<VERSION_BEFORE_15>
sudo apt-mark hold client-security
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list client-security
sudo dnf downgrade client-security-<VERSION_BEFORE_15>
sudo dnf versionlock add client-security
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.
withsecure elements endpoint protection DOWNGRADE
Affected: >= 17
Fixed in: no fixed release known
Safe to downgrade to: a release before 17
1. Check installed version
apt-cache policy elements-endpoint-protection || rpm -q elements-endpoint-protection || elements-endpoint-protection --version
2. No fixed release: DOWNGRADE to a release before 17 (Debian / Ubuntu)
apt-cache madison elements-endpoint-protection
sudo apt install elements-endpoint-protection=<VERSION_BEFORE_17>
sudo apt-mark hold elements-endpoint-protection
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list elements-endpoint-protection
sudo dnf downgrade elements-endpoint-protection-<VERSION_BEFORE_17>
sudo dnf versionlock add elements-endpoint-protection
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.
withsecure email and server security DOWNGRADE
Affected: 15
Fixed in: no fixed release known
Safe to downgrade to: a release before 15
1. Check installed version
apt-cache policy email-and-server-security || rpm -q email-and-server-security || email-and-server-security --version
2. No fixed release: DOWNGRADE to a release before 15 (Debian / Ubuntu)
apt-cache madison email-and-server-security
sudo apt install email-and-server-security=<VERSION_BEFORE_15>
sudo apt-mark hold email-and-server-security
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list email-and-server-security
sudo dnf downgrade email-and-server-security-<VERSION_BEFORE_15>
sudo dnf versionlock add email-and-server-security
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.
withsecure server security DOWNGRADE
Affected: 15
Fixed in: no fixed release known
Safe to downgrade to: a release before 15
1. Check installed version
apt-cache policy server-security || rpm -q server-security || server-security --version
2. No fixed release: DOWNGRADE to a release before 15 (Debian / Ubuntu)
apt-cache madison server-security
sudo apt install server-security=<VERSION_BEFORE_15>
sudo apt-mark hold server-security
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list server-security
sudo dnf downgrade server-security-<VERSION_BEFORE_15>
sudo dnf versionlock add server-security
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.
withsecure linux protection DOWNGRADE
Affected: 12.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 12.0
1. Check installed version
apt-cache policy linux-protection || rpm -q linux-protection || linux-protection --version
2. No fixed release: DOWNGRADE to a release before 12.0 (Debian / Ubuntu)
apt-cache madison linux-protection
sudo apt install linux-protection=<VERSION_BEFORE_12.0>
sudo apt-mark hold linux-protection
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list linux-protection
sudo dnf downgrade linux-protection-<VERSION_BEFORE_12.0>
sudo dnf versionlock add linux-protection
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.
withsecure linux security 64 DOWNGRADE
Affected: 12.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 12.0
1. Check installed version
apt-cache policy linux-security-64 || rpm -q linux-security-64 || linux-security-64 --version
2. No fixed release: DOWNGRADE to a release before 12.0 (Debian / Ubuntu)
apt-cache madison linux-security-64
sudo apt install linux-security-64=<VERSION_BEFORE_12.0>
sudo apt-mark hold linux-security-64
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list linux-security-64
sudo dnf downgrade linux-security-64-<VERSION_BEFORE_12.0>
sudo dnf versionlock add linux-security-64
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.
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.
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-2023-42521?
client security: downgrade or apply the listed mitigation; elements endpoint protection: downgrade or apply the listed mitigation; email and server security: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2023-42521 being exploited?
CVE-2023-42521 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-2023-42521 affect?
CVE-2023-42521 affects client security, elements endpoint protection, email and server security. Severity is high (CVSS 7.5). Certain WithSecure products allow a remote crash of a scanning engine via processing of a compressed file. This affects WithSecure Client Security 15, WithSecure Server Security 15, WithSecure Email and Server Security 15, WithSecure Elemen
How urgent is CVE-2023-42521?
Priority 49/100. High severity; Remotely exploitable, no login, no user action; On your watchlist
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