What’s Vulnerable › Vulnerabilities

CVE-2026-67298: FreeRDP 3.28.0 Heap Buffer Overflow via RAIL orderLength Underflow

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-01 · updated 2026-08-31
• Weakness: CWE-191

Description

FreeRDP versions 3.28.0 and earlier contain a heap buffer overflow in the server-side RAIL channel handler (rail_server_handle_messages() in channels/rail/server/rail_main.c). When processing a RAIL PDU header, the code subtracts RAIL_PDU_HEADER_LENGTH from the peer-controlled orderLength field without first verifying orderLength is at least the header length. For orderLength values 0..3 this causes an unsigned integer underflow to a very large size, which bypasses the Stream_EnsureRemainingCapacity() capacity check (due to pointer arithmetic wraparound) and is then passed to WTSVirtualChannelRead(), resulting in an out-of-bounds heap write. A malicious or compromised RDP client can exploit this to corrupt the heap and crash the server. Fixed in FreeRDP 3.29.0.

Affected products

• FreeRDP: before 3.29.0 — fixed in 3.29.0

How to fix

Upgrade to a fixed version: FreeRDP 3.29.0. Check the vendor advisory for mitigations.

References

• https://github.com/FreeRDP/FreeRDP/commit/46848765f2a1134f8652f8760eefb5e85d64a9b8
• https://github.com/FreeRDP/FreeRDP/commit/5370fb26fbf034ecd11d3026b6ad639b5fff493f
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-qmvw-52ph-q5pv
• https://www.vulncheck.com/advisories/freerdp-heap-buffer-overflow-via-rail-orderlength-underflow
• https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-5wr6-8m8j-3h7f

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