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RCE in Windows Routing and Remote Access Service (RRAS) via heap-based buffer overflow

IdentifiersCVE-2026-20868CWE-122· Heap-based Buffer Overflow

CVE-2026-20868 is a heap-based buffer overflow vulnerability in Microsoft Windows Routing and Remote Access Service (RRAS). The issue is remotely reachable (AV:N) and, per the provided reporting, can be triggered when a user is tricked into connecting to a malicious RRAS server, resulting in a heap overflow condition and enabling arbitrary code execution on the vulnerable RRAS system. The associated CVSS v3.1 vector is AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, and the weakness class is CWE-122.

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For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can result in remote code execution in the context of the vulnerable RRAS service, with high impact to confidentiality, integrity, and availability (C:H/I:H/A:H per the provided CVSS vector).

Mitigation

If you can’t patch tonight, do this now.

Until patches can be deployed, reduce exposure of RRAS by limiting/controlling RRAS usage and access paths, and prevent users/systems from connecting to untrusted RRAS servers (e.g., via network controls and policy).

Remediation

Patch, then assume compromise.

Apply Microsoft’s security update for CVE-2026-20868 as provided via the MSRC Update Guide entry for this CVE.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Microsoft CorporationWindows 10 1607operating_system
Microsoft CorporationWindows 10 1809operating_system
Microsoft CorporationWindows 10 21h2operating_system
Microsoft CorporationWindows 10 22h2operating_system
Microsoft CorporationWindows 11 23h2operating_system
Microsoft CorporationWindows 11 24h2operating_system
Microsoft CorporationWindows 11 25h2operating_system
Microsoft CorporationWindows Server 2008operating_system
Microsoft CorporationWindows Server 2008 R2operating_system
Microsoft CorporationWindows Server 2008 Sp2operating_system
Microsoft CorporationWindows Server 2012operating_system
Microsoft CorporationWindows Server 2012 R2operating_system
Microsoft CorporationWindows Server 2016operating_system
Microsoft CorporationWindows Server 2019operating_system
Microsoft CorporationWindows Server 2022operating_system
Microsoft CorporationWindows Server 2022 23h2operating_system
Microsoft CorporationWindows Server 2025operating_system
Microsoft CorporationWindows Server 23h2operating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2

Community discussion across Reddit, Mastodon, and other social sources.