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CVE-2026-57979 is an information disclosure vulnerability residing in the Windows Remote Desktop Protocol (RDP) stack. The flaw is classified as an out-of-bounds read (CWE-125) and stems from improper boundary validation when the RDP service processes certain network packets. Under normal operations, the RDP parser reads data from allocated buffers to handle session negotiation, channel setup, and graphics rendering. In this instance, a missing length check allows the parser to continue reading past the intended buffer boundary, pulling adjacent heap memory contents into the response stream.
The attack vector is remote and requires no authentication (AV:N/AC:L/PR:N), but it does demand user interaction (UI:R) — the victim must initiate or accept an RDP connection while the attacker is positioned on the network. This interaction can be as subtle as a user clicking a malicious .rdp file or connecting to a rogue RDP server. Once the connection is established, the attacker can send specially crafted RDP packets that trigger the over-read, causing the server to echo back memory regions that were never meant to be transmitted.
Because the read is out-of-bounds, the leaked data may include session tokens, NTLM hashes, Kerberos tickets, partial credentials, or even sensitive application data that happened to reside in the freed or uninitialized heap. The CVSS vector (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N) reflects a high confidentiality impact, though integrity and availability remain unaffected. The vulnerability is rated as “Important” by Microsoft and carries a base score of 6.5 (MEDIUM).
Affected products span a broad range of Windows client and server versions, including Windows 10 (1607, 1809, 21H2, 22H2), Windows 11 (24H2, 25H2, 26H1), and Windows Server (2012, 2012 R2, 2016, 2019, 2022, 2025). Microsoft addressed the issue through the July 2026 Patch Tuesday cumulative updates, released on July 14, 2026. At the time of disclosure, no public proof-of-concept or active in-the-wild exploitation had been observed, and the exploitability index classified it as “less likely” to be exploited. However, the potential for memory leakage makes it a serious concern for enterprises relying on RDP for remote administration and virtual desktop infrastructure.
The vulnerability is one of five RDP information-disclosure flaws patched in the same update cycle, all sharing similar memory-safety roots. While the immediate risk is data exposure, an attacker could combine this read primitive with other vulnerabilities to escalate privileges or bypass memory mitigations like ASLR. Administrators are urged to treat this as a high-priority patch, especially in environments where RDP is exposed to untrusted networks.
DailyCVE Form:
Platform: Windows RDP
Version: 10/11/Server
Vulnerability: Out-of-bounds Read
Severity: MEDIUM (6.5)
date: July 14 2026
Prediction: Patch released Jul14
What Undercode Say:
Analytics:
- Monitor RDP logs for anomalous session patterns.
- Use the following PowerShell to check installed KBs for July 2026:
Get-HotFix | Where-Object {$_.InstalledOn -ge [bash]"2026-07-14"} | Select-Object HotFixID, Description, InstalledOn - To inventory systems with RDP enabled, run:
Linux/macOS (nmap) nmap -p 3389 --open <target_network>/24 Windows (PowerShell) Get-NetTCPConnection -LocalPort 3389 | Where-Object {$_.State -eq "Listen"} - Query the MSRC update table for CVE-2026-57979 using the official Microsoft Update Catalog API (conceptual):
curl -X GET "https://api.microsoft.com/update/catalog?cve=CVE-2026-57979" -H "Accept: application/json"
Exploit:
- No public exploit is currently available.
- Theoretical attack: send a crafted RDP packet with a malformed length field in the `RDP_BITMAP_DATA` or `RDP_ORDER_HEADER` structure, causing the server to read beyond the allocated buffer and include heap memory in the response.
- Requires the victim to connect to a malicious RDP server or open a malicious .rdp file (user interaction).
- Unauthenticated remote attacker can trigger the over-read without credentials.
Protection:
- Apply the July 2026 cumulative updates (Patch Tuesday) via Windows Update or the Microsoft Update Catalog.
- Restrict inbound RDP traffic to trusted IP ranges using Windows Firewall or network ACLs.
- Enable Network Level Authentication (NLA) to add an extra layer of authentication before session establishment.
- Disable RDP if not required, or use a VPN/gateway to encapsulate RDP traffic.
- Monitor for unusual RDP connection attempts and review event logs (Event ID 4625, 4624) for anomalies.
Impact:
- High confidentiality impact: exposure of heap memory contents, potentially including credentials, session keys, Kerberos tickets, NTLM hashes, and other sensitive data.
- No integrity or availability impact (read-only flaw).
- Can aid lateral movement and privilege escalation when combined with other vulnerabilities.
- Particularly dangerous in VDI and cloud-hosted environments where RDP sessions handle elevated privileges and sensitive corporate data.
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Sources:
Reported By: nvd.nist.gov
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