Security readout for executives and security teams
Plain-English summary
A malicious RDP client can send a malformed clipboard message to a vulnerable FreeRDP server, corrupting server memory. This can remotely crash the service and might enable code execution, although code execution has not been confirmed. FreeRDP versions before 3.26.0 are affected.
Executive priority
Treat this as an expedited high-priority update for exposed FreeRDP servers. The vulnerability is remotely reachable by a client and can disrupt service, with potentially greater impact if code execution proves practical. Prioritize internet-facing, shared, or otherwise untrusted-client environments. Current evidence does not justify describing it as actively exploited or critical.
Technical view
FreeRDP before 3.26.0 insufficiently validates capabilitySetLength while parsing a CB_CLIP_CAPS PDU in the server-side cliprdr channel. An undersized value can cause a heap-buffer-overflow write. CVSS 3.1 rates it 8.8 with network reachability, low complexity, low privileges, no user interaction, and potentially severe confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to FreeRDP versions below 3.26.0 where server-side clipboard-channel processing is reachable by RDP clients. Risk is highest for servers accepting connections from untrusted or low-privileged clients. Client-only deployments may not expose the described server-side path; confirm actual roles and configuration.
Exploitation context
The supplied record does not establish active exploitation, and the CVE is not listed as KEV. Remote denial of service is supported by the described crash condition. Code execution is considered possible because heap memory is overwritten, but no cited source confirms successful code execution. The cpp-httplib advisory is unrelated and does not support exploitation claims for FreeRDP.
Researcher notes
Focus validation on bounds handling for capabilitySetLength in CB_CLIP_CAPS parsing and the affected server-side cliprdr path. CWE-122 and CWE-131 describe the heap overwrite and size-calculation weaknesses. Avoid treating the unrelated cpp-httplib advisory's exploit tag as evidence. Public evidence supplied here does not confirm a working exploit or code-execution outcome.
Mitigation direction
- Upgrade upstream FreeRDP to version 3.26.0 or later.
- Apply supported distribution updates, including applicable Red Hat errata.
- Until patched, restrict RDP server access to trusted clients and networks.
- Consult current vendor guidance if an immediate upgrade is unavailable.
Validation and detection
- Inventory FreeRDP packages and confirm their effective versions.
- Identify deployments operating as RDP servers with server-side clipboard processing.
- Verify remediation provides FreeRDP 3.26.0 or the distribution's backported fix.
- Retest expected RDP and clipboard workflows after updating.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-122: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-131: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-44420 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9GitHub_MCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-29T21:01:57.327Z: Reported to Red Hat.
- 2026-05-29T19:42:23.460Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-mvpx-xj7r-3p3rCVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8CVE reference, CISA-ADP · exploit
- https://access.redhat.com/security/cve/CVE-2026-44420CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2483480CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44420.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:46393CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:36203CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Heap-based Buffer Overflow
Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Incorrect Calculation of Buffer Size
Incorrect Calculation of Buffer Size represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.