Client heap corruption via unbounded routing token
Published Sep 15, 2026 · Updated Sep 15, 2026
Heap-based buffer overflow in FreeRDP before 3.31.0 allows remote attackers to crash clients through a malicious RDP server. nego_send_negotiation_request() copies an unbounded LB_LOAD_BALANCE_INFO routing token into a fixed 512-byte heap stream before checking its length. A client must connect to a malicious server or accept an unsigned redirection PDU; the default path is pre-authentication, and the controlled overwrite can corrupt the heap or terminate the client.
Summary
What happened
Heap-based buffer overflow in FreeRDP before 3.31.0 allows remote attackers to crash clients through a malicious RDP server. nego_send_negotiation_request() copies an unbounded LB_LOAD_BALANCE_INFO routing token into a fixed 512-byte heap stream before checking its length. A client must connect to a malicious server or accept an unsigned redirection PDU; the default path is pre-authentication, and the controlled overwrite can corrupt the heap or terminate the client.
The record
- CVE
- CVE-2026-91953
- 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
- Sep 15, 2026CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=0 <3.31.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- Oversized LB_LOAD_BALANCE_INFO crash reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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