PatchTheCVECVE-2023-43761: Certain WithSecure products allow Denial of Service (infinite loop)
49
This month
HIGH 7.5REMOTEWATCHLISTDOWNGRADEDOWNGRADEDOWNGRADE
CVE-2023-43761 is a high-severity flaw (CVSS 7.5) affecting linux protection, linux security 64, atlant. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
Certain WithSecure products allow Denial of Service (infinite loop). 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 (formerly F-Secure Atlant) 1.0.35-1.
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 50%) |
| CISA exploited list | No |
| Weakness | CWE-835 |
| Published | 2023-09-22 |
| Last modified | 2026-06-17 |
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
f-secure 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.
f-secure 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.
f-secure atlant DOWNGRADE
Affected: 1.0.35-1
Fixed in: no fixed release known
Safe to downgrade to: a release before 1.0.35-1
1. Check installed version
apt-cache policy atlant || rpm -q atlant || atlant --version
2. No fixed release: DOWNGRADE to a release before 1.0.35-1 (Debian / Ubuntu)
apt-cache madison atlant
sudo apt install atlant=<VERSION_BEFORE_1.0.35-1>
sudo apt-mark hold atlant
2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list atlant
sudo dnf downgrade atlant-<VERSION_BEFORE_1.0.35-1>
sudo dnf versionlock add atlant
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.
f-secure client security DOWNGRADE
Affected: 15.00
Fixed in: no fixed release known
Safe to downgrade to: a release before 15.00
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 15.00 (Debian / Ubuntu)
apt-cache madison client-security
sudo apt install client-security=<VERSION_BEFORE_15.00>
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_15.00>
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.
f-secure elements endpoint protection DOWNGRADE
Affected: >= 17.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 17.0
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 17.0 (Debian / Ubuntu)
apt-cache madison elements-endpoint-protection
sudo apt install elements-endpoint-protection=<VERSION_BEFORE_17.0>
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_17.0>
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.
f-secure email and server security DOWNGRADE
Affected: 15.00
Fixed in: no fixed release known
Safe to downgrade to: a release before 15.00
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 15.00 (Debian / Ubuntu)
apt-cache madison email-and-server-security
sudo apt install email-and-server-security=<VERSION_BEFORE_15.00>
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_15.00>
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.
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-2023-43761?
linux protection: downgrade or apply the listed mitigation; linux security 64: downgrade or apply the listed mitigation; atlant: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2023-43761 being exploited?
CVE-2023-43761 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-2023-43761 affect?
CVE-2023-43761 affects linux protection, linux security 64, atlant. Severity is high (CVSS 7.5). Certain WithSecure products allow Denial of Service (infinite loop). This affects WithSecure Client Security 15, WithSecure Server Security 15, WithSecure Email and Server Security 15, WithSecure Elements Endpoint Protection 17 and later, W
How urgent is CVE-2023-43761?
Priority 49/100. High severity; Remotely exploitable, no login, no user action; On your watchlist
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