CVE-2026-91964Public exploitNetwork attack vectorHinoki check available

Client crash or code execution via RoutingToken overflow

Published Sep 15, 2026 · Updated Sep 15, 2026

Heap buffer overflow in FreeRDP 2.0.0 through 3.30.0 allows remote attackers to crash RDP clients or execute code via server redirection. During reconnection, nego_send_negotiation_request copies the server-controlled RoutingToken into a fixed 512-byte heap stream without checking capacity. A victim must connect to a malicious RDP server; the overflow crashes the client, while code execution requires a separate memory disclosure to defeat ASLR.

CVSS severity8.8
High
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Heap buffer overflow in FreeRDP 2.0.0 through 3.30.0 allows remote attackers to crash RDP clients or execute code via server redirection. During reconnection, nego_send_negotiation_request copies the server-controlled RoutingToken into a fixed 512-byte heap stream without checking capacity. A victim must connect to a malicious RDP server; the overflow crashes the client, while code execution requires a separate memory disclosure to defeat ASLR.

The record

CVE
CVE-2026-91964
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
FreeRDP
Product
FreeRDP
Classifications
CWE-122, CWE-787, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.31.0
  2. Affected versionversion=2.0.0 <3.0.0
  3. Affected versionversion=3.0.0 <3.31.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FreeRDP · FreeRDPversion=0 <3.31.0; version=2.0.0 <3.0.0; version=3.0.0 <3.31.0

Published CVSS scores

8.8FreeRDP GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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