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CVE-2026-91948— FreeRDP before 3.31.0 Out-of-bounds Write via SHOW_PROTOCOL

Quick assessment

Affected
FreeRDP FreeRDP
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

FreeRDP 3.31.0 之前的版本存在一个越界写漏洞，该漏洞位于启用 CHANNEL_OPTION_SHOW_PROTOCOL 选项时的服务器端静态虚拟通道处理中。经过认证的客户机能够排队提交过大的通道消息，从而导致缓冲区下溢，破坏堆内存（包括活动指针），进而可能实现代码执行。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 2

VendorProduct Version RangeStatus
FreeRDP FreeRDP 3.28.0< 3.31.0 affected
3.31.0 unaffected
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I. Basic Information for CVE-2026-91948

Vulnerability Information
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Vulnerability Title
FreeRDP before 3.31.0 Out-of-bounds Write via SHOW_PROTOCOL
Source: CVE Program / CVE List V5
Vulnerability Description
FreeRDP versions before 3.31.0 contain an out-of-bounds write vulnerability in server-side static virtual channel handling when CHANNEL_OPTION_SHOW_PROTOCOL is enabled. Authenticated clients can queue oversized channel messages that cause buffer underflow and corrupt heap memory including live pointers, potentially enabling code execution.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeRDP FreeRDP 3.28.0 ~ 3.31.0 -

II. Public POCs for CVE-2026-91948

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III. Intelligence Information for CVE-2026-91948

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Patches & Fixes for CVE-2026-91948 (1)

Vendor Advisories for CVE-2026-91948 (2)

Same Patch Batch · FreeRDP · 2026-09-15 · 20 CVEs total

CVE-2026-91949 9.3 CRITICAL FreeRDP 3.0.0 through 3.30.0 Protocol Negotiation Bypass
CVE-2026-91964 8.8 HIGH FreeRDP 2.0.0 through 3.30.0 Heap Buffer Overflow via RoutingToken
CVE-2026-91947 7.5 HIGH FreeRDP Server before 3.31.0 Use-After-Free via DRDYNVC
CVE-2026-91955 7.5 HIGH FreeRDP before 3.31.0 Denial of Service via Desktop Dimensions
CVE-2026-91958 6.6 MEDIUM FreeRDP 3.11.0 through 3.30.0 Heap Buffer Overflow via Monitor Index
CVE-2026-91960 6.5 MEDIUM FreeRDP before 3.31.0 Integer Overflow Double Free
CVE-2026-91959 6.5 MEDIUM FreeRDP before 3.31.0 Buffer Over-read via RTS Gateway
CVE-2026-91945 6.5 MEDIUM FreeRDP before 3.31.0 Out-of-bounds Read via Smartcard ATR
CVE-2026-91952 6.5 MEDIUM FreeRDP before 3.31.0 Denial of Service via pool_decode_rect
CVE-2026-91950 6.5 MEDIUM FreeRDP before 3.31.0 Out-of-Bounds Read via UINT32 Wraparound
CVE-2026-91954 6.5 MEDIUM FreeRDP before 3.31.0 NULL Pointer Dereference via NSCodec
CVE-2026-91963 6.5 MEDIUM FreeRDP 2.0.0 through 3.30.0 Uninitialized Heap Memory Disclosure via urbdrc
CVE-2026-91961 6.5 MEDIUM FreeRDP before 3.31.0 Denial of Service via URBDRC
CVE-2026-91953 6.5 MEDIUM FreeRDP before 3.31.0 Heap Buffer Overflow via LB_LOAD_BALANCE_INFO
CVE-2026-91946 6.5 MEDIUM FreeRDP before 3.31.0 Information Disclosure via RDPGFX ResetGraphics
CVE-2026-91951 6.5 MEDIUM FreeRDP 3.14.0 through 3.30.0 Out-of-bounds Write via urbdrc
CVE-2026-91956 6.5 MEDIUM FreeRDP before 3.31.0 Out-of-Bounds Read via URBDRC
CVE-2026-91962 6.3 MEDIUM FreeRDP before 3.31.0 Integer Overflow via audin Apple backends
CVE-2026-91957 3.1 LOW FreeRDP before 3.31.0 Use-After-Free via smartcard worker

IV. Related Vulnerabilities

Same product: FreeRDP
Same vendor: FreeRDP
Same weakness: CWE-191

V. Comments for CVE-2026-91948

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