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FreerdpApplication

CVE-2026-23534

CRITICAL · 9.8 CVSS v3.1 Published 2026-01-19
Fix available
A fix is available. Upgrade to 3.21.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit 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
FreeRDP is a free implementation of the Remote Desktop Protocol. Prior to version 3.21.0, a client-side heap buffer overflow occurs in the ClearCodec bands decode path when crafted band coordinates allow writes past the end of the destination surface buffer. A malicious server can trigger a client‑side heap buffer overflow, causing a crash (DoS) and potential heap corruption with code‑execution risk depending on allocator behavior and surrounding heap layout. Version 3.21.0 contains a patch for the issue.

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 · high confidence

FreeRDP prior to 3.21.0 contains a client-side heap buffer overflow in the ClearCodec bands decode path. When a malicious RDP server sends crafted band coordinates, the client writes past the end of the destination surface buffer, causing potential heap corruption, denial of service, and possible code execution depending on heap layout.

MitigationUpgrade FreeRDP clients to version 3.21.0 or later to obtain the patch. Until upgraded, restrict RDP connections to trusted servers to avoid malicious server exploitation.

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
FreerdpApplication
Affected:< 3.21.0

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 FreeRDP installation
    Run 'freerdp-version' or 'freerdp-get version' to get the installed FreeRDP client version. On Linux, also try 'dpkg -l | grep freerdp' or 'rpm -qa | grep freerdp'.
    Affected if The installed version is less than 3.21.0 (e.g., 3.20.0, 3.19.x, 2.x, etc.)
  2. Confirm client usage
    FreeRDP must be used as an RDP client to connect to remote servers. Verify you have freerdp-client, xfreerdp, or wfreerdp executables installed and usable on the system.
    Affected if FreeRDP client binaries are installed and available for making RDP connections.
  3. Verify ClearCodec is enabled by default
    The vulnerability exists in the ClearCodec bands decode path. When connecting to an RDP server using FreeRDP client (e.g., 'xfreerdp /v:server'), the ClearCodec is used if the server supports it - this is the default behavior for most connections.
    Affected if You connect to RDP servers using FreeRDP client, as the malicious server can trigger the vulnerability during normal codec negotiation.
  4. Check network exposure
    Assess whether FreeRDP clients connect to untrusted or internet-facing RDP servers. Review connection patterns, saved connection profiles, or scripts that invoke xfreerdp/wfreerdp.
    Affected if FreeRDP clients connect to servers that are not fully trusted or are exposed to potential malicious RDP servers.

You are affected if FreeRDP client version is below 3.21.0 AND you use it to connect to RDP servers, particularly untrusted ones, as the vulnerability triggers when a malicious server sends crafted band coordinates during ClearCodec processing.

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.

dbcve · scoped
Upgrade available Upgrade to 3.21.0 or later
Fixed in 3.21.0
Interim mitigation

Upgrade FreeRDP clients to version 3.21.0 or later to obtain the patch. Until upgraded, restrict RDP connections to trusted servers to avoid malicious server exploitation.

Recommended fix High confidence

FreeRDP 3.21.0

  1. 1. Identify the current FreeRDP version installed on the system (e.g., using package manager or freerdp-version command)
  2. 2. Upgrade FreeRDP to version 3.21.0 or later using the appropriate package manager or build from source
  3. 3. Verify the installed FreeRDP version is 3.21.0 or higher to confirm the patch was applied
  4. 4. Test FreeRDP connections to ensure normal functionality after upgrade

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Freerdp Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

Scan for this in your stack

Free · runs locally
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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-2026-23534 in production — separate from our analysis above.

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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