dbcve.org
Client SecurityApplication · Withsecure

CVE-2023-42521

HIGH · 7.5 CVSS v3.1 Published 2023-09-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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 (formerly F-Secure Atlant) 1.0.35-1.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

WithSecure scanning engine contains a vulnerability that can be triggered by processing a specially crafted compressed file, leading to a remote denial of service (crash). The issue affects the scanning engine component across multiple product lines including endpoint protection for Windows, Mac, and Linux platforms.

MitigationApply available vendor patches or update to newer versions of the affected WithSecure products to remediate this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Client SecurityApplication
Affected:= 15
Elements Endpoint ProtectionApplication
Affected:>= 17
Email And Server SecurityApplication
Affected:= 15
Server SecurityApplication
Affected:= 15
Linux ProtectionApplication
Affected:= 12.0
Linux Security 64Application
Affected:= 12.0
AtlantApplication
Affected:= 1.0.35-1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed WithSecure product
    Use system inventory or package manager to list installed security products. On Windows, check 'Programs and Features' or registry under HKLM\Software\WithSecure. On Linux, check rpm/dpkg packages or look for /opt/f-secure or /opt/withsecure directories.
    Affected if No WithSecure product is found (not affected). If a WithSecure product is present, proceed to version check.
  2. Determine exact product version
    For Windows products, run 'Get-ItemProperty' on the installed product registry key or use the product's own about/version dialog. For Linux, run 'rpm -qi' or 'dpkg -l' on the specific package name (such as f-secure-linux-protection, withsecure-client-security, or similar).
    Affected if Unable to determine version (requires manual investigation).
  3. Compare version against affected ranges
    Match your installed product and version against: Client Security =15, Elements Endpoint Protection >=17, Email And Server Security =15, Server Security =15, Linux Protection =12.0, Linux Security 64 =12.0, Atlant =1.0.35-1. Use exact string comparison for '=' versions and numeric comparison for '>=' versions.
    Affected if Installed version matches one of the affected version specifications.
  4. Verify scanning engine component is active
    Check if the WithSecure real-time scanning or on-demand scanning service is enabled and running. On Windows, check the WithSecure service status in Services.msc. On Linux, check process status of 'sdc' or 'fsdaemon' and look for scanning daemon processes.
    Affected if Scanning engine component is disabled or not running (reduced exploit surface but version may still be vulnerable).

A user is affected if they have any of the listed WithSecure products installed with a version matching the specified affected ranges and the scanning engine component is active or capable of being triggered.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply available vendor patches or update to newer versions of the affected WithSecure products to remediate this vulnerability.

Fix this in Client Security Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2023-42521 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-42521 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data