High severity · published Aug 1, 2026
CVE-2026-67300
FreeRDP before 3.29.0 Use-After-Free via async message proxy
7.5
CVSS
0.3%
EPSS
No
On KEV
Description
FreeRDP before 3.29.0 contains client-side heap use-after-free vulnerabilities in the async update message proxy for RAIL WINDOW_STATE_ORDER and NOTIFY_ICON_STATE_ORDER when AsyncUpdate is enabled. When a malicious or compromised RDP server sends crafted update orders, the message proxy shallow-copies structures containing nested parser-owned pointers (e.g., titleInfo.string, windowRects, visibilityRects, icon buffers). The parser frees those nested buffers after the callback returns, so the queued async message later dispatches stale pointers, potentially causing memory corruption or a client crash.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 25% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
FR
FreeRDP · FreeRDP
before 3.29.0 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-67300
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-67300
github.com
https://github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f
github.com
https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-33gg-h66j-3697
www.vulncheck.com
https://www.vulncheck.com/advisories/freerdp-before-use-after-free-via-async-message-proxy
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