Security readout for executives and security teams
Plain-English summary
CVE-2026-22856 affects FreeRDP before 3.20.1. A timing bug in serial-channel thread tracking can cause memory to be used after it was freed. The vendor states it is fixed in 3.20.1. Treat this as a patch-priority issue for systems where FreeRDP is used to initiate RDP connections.
Executive priority
Schedule remediation in the next normal security update cycle, sooner for heavily used remote access environments. The issue can affect confidentiality, integrity, and availability of the vulnerable system, but current evidence indicates high exploitation complexity and no confirmed active exploitation.
Technical view
FreeRDP has a race condition in create_irp_thread affecting serial->IrpThreads. One thread can remove an entry while another reads it, leading to heap use-after-free. The provided CVSS 4.0 score is 6.8 with network attack vector, high attack complexity, no privileges required, passive user interaction, and high vulnerable-system confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to FreeRDP versions earlier than 3.20.1. Risk depends on where FreeRDP is installed directly or embedded in products, images, appliances, or Linux distribution packages. The issue is tied to the serial channel, so vulnerability managers should verify whether affected builds and relevant functionality are present.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. The CVSS vector includes proof-of-concept exploit maturity, but exploitation is high complexity and requires passive user interaction. Do not assume internet-wide exploitation from the provided evidence.
Researcher notes
Key focus areas are serial-channel IRP thread lifecycle and concurrent access to serial->IrpThreads. The advisory identifies CWE-362 and CWE-416. Evidence provided does not include exploit details, crash traces, or affected downstream distributions, so confirm exposure against actual FreeRDP build provenance.
Mitigation direction
- Upgrade FreeRDP to version 3.20.1 or later.
- Prioritize updates on systems that initiate RDP sessions using FreeRDP.
- Check operating system or product vendor packages for backported fixes.
- If you cannot update, monitor FreeRDP and distribution guidance for supported workarounds.
Validation and detection
- Inventory installed FreeRDP versions across endpoints, servers, containers, and images.
- Confirm all detected versions are 3.20.1 or later, or vendor-patched.
- Review dependency manifests for applications embedding FreeRDP.
- Track the GitHub advisory and 3.20.1 release notes for implementation details.
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-362: 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-416: 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 lookupCVE-2026-22856 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
- Medium
- CVSS
- 6.8 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
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.
CVSS vector scores
1 official scoreWe 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:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
6.8MediumVector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-w842-c386-fxhvCVE reference · x_refsource_CONFIRM
- https://github.com/FreeRDP/FreeRDP/releases/tag/3.20.1CVE reference · x_refsource_MISC
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.