Windows RRAS CVE-2026-69852

The target Windows system must have the Routing and Remote Access Service (RRAS) installed and actively running - RRAS is not enabled by default on Windows desktop editions but is commonly deployed on Windows Server for VPN hosting, site-to-site routing, or NAT. The attacker must have low-privilege authenticated access (PR:L per CVSS), meaning some form of credential or network-layer authentication to interact with the RRAS service is required; completely unauthenticated exploitation is not indicated by the CVSS vector. High attack complexity (AC:H) imposes a further barrier: specific heap-layout or timing conditions must be satisfied for the overflow to achieve reliable code execution, limiting reliable exploitation to skilled or well-resourced attackers. Systems with RRAS disabled or stopped, systems where RRAS ports are firewalled from untrusted networks, and systems patched to the fixed build versions are not exploitable.

The CVSS 3.1 vector AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H scores 7.5, capturing a meaningful tension between full-impact potential and real-world exploitability constraints. The AC:H metric indicates that heap-layout conditions, timing, or precise packet construction must align for reliable exploitation, substantially reducing the prospect of automated mass scanning campaigns compared to AC:L flaws. PR:L confirms that some form of authenticated or credentialed access to the RRAS service is required, ruling out completely unauthenticated internet-facing exploitation scenarios. No EPSS score was available in the provided data, so exploitation probability cannot be quantified numerically. The CVE is not listed in CISA KEV and no public proof-of-concept has been identified, suggesting this remains a theoretical or researcher-held capability at time of writing. Nonetheless, the C:H/I:H/A:H impact triad and the extremely wide affected-version footprint - covering actively used enterprise platforms from Server 2016 through Server 2025 - mean that even a mid-sized municipal IT team in walbrzych should treat this as urgent patching work, particularly for internet-facing or VPN-hosting Windows Server deployments. The absence of KEV listing and POC does not confirm non-exploitation; it reflects a gap in available intelligence.

An attacker with low-level network credentials - such as a VPN user or domain account with RRAS access - sends a specially crafted protocol packet to a Windows Server running RRAS. Under specific heap-layout conditions (reflected in AC:H), the malformed packet triggers a heap-based buffer overflow in the RRAS service process, allowing the attacker to overwrite adjacent heap metadata, corrupt a function pointer, and redirect execution to attacker-controlled shellcode, achieving full remote code execution on the server. No public proof-of-concept has been identified, but the technique is a well-understood exploit class for heap overflow vulnerabilities.