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CVE-2026-91953— FreeRDP before 3.31.0 Heap Buffer Overflow via LB_LOAD_BALANCE_INFO

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 之前的版本中， 函数存在堆缓冲区溢出漏洞。该函数在将数据写入固定的 512 字节缓冲区之前，未验证 字段的长度。恶意的 RDP 服务器或中间人攻击者可以发送一个携带过大 值的服务器重定向 PDU，从而用攻击者可控的内容导致缓冲区溢出，进而在认证完成前造成拒绝服务或堆内存损坏。

CVSS 6.5 · Medium

Affected Version Matrix 2

VendorProduct Version RangeStatus
FreeRDP FreeRDP < 3.31.0 affected
3.31.0 unaffected
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I. Basic Information for CVE-2026-91953

Vulnerability Information
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Vulnerability Title
FreeRDP before 3.31.0 Heap Buffer Overflow via LB_LOAD_BALANCE_INFO
Source: CVE Program / CVE List V5
Vulnerability Description
FreeRDP versions before 3.31.0 contain a heap buffer overflow vulnerability in nego_send_negotiation_request() that fails to validate the LB_LOAD_BALANCE_INFO field length before writing to a fixed 512-byte buffer. A malicious RDP server or man-in-the-middle can send a Server Redirection PDU with an oversized LB_LOAD_BALANCE_INFO value to overflow the buffer with attacker-controlled content, causing denial of service or heap corruption before authentication completes.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
未进行输入大小检查的缓冲区拷贝(传统缓冲区溢出)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
FreeRDP FreeRDP 0 ~ 3.31.0 -

II. Public POCs for CVE-2026-91953

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III. Intelligence Information for CVE-2026-91953

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Vendor Advisories for CVE-2026-91953 (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-2026-91948 7.5 HIGH FreeRDP before 3.31.0 Out-of-bounds Write via SHOW_PROTOCOL
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-2026-91945 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-2026-91959 6.5 MEDIUM FreeRDP before 3.31.0 Buffer Over-read via RTS Gateway
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-2026-91950 6.5 MEDIUM FreeRDP before 3.31.0 Out-of-Bounds Read via UINT32 Wraparound
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-120

V. Comments for CVE-2026-91953

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