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Out-of-Bounds Write in D-Link DIR-822A L2TP Control Message Parser
CVE-2026-86510 is an out-of-bounds write vulnerability in the L2TP Control Message Parser of D-Link DIR-822A firmware A_101. The flaw is located in the tunnel_set_params function and can be triggered using specially crafted L2TP control-message data, including the L2TP Host Name AVP processing path. The resulting write beyond an allocated memory region causes attacker-influenced memory corruption.
What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.
What an attacker gets, and what they’ve been doing with it.
Successful exploitation can cause arbitrary memory corruption and has high confidentiality, integrity, and availability impact. Depending on memory layout and device protections, the condition may enable denial of service, compromise of the affected router, or code execution. CVSS v3.1 is 9.9 and indicates high impacts across confidentiality, integrity, and availability with changed scope.
If you can’t patch tonight, do this now.
Until a vendor firmware update applicable to the exact DIR-822A hardware revision is available, do not expose router administration or L2TP-facing services to the Internet. Disable unnecessary remote-management functionality, restrict administrative access to trusted systems through firewall or network-access controls, and limit L2TP/L2TPv6 WAN use where operationally feasible. Monitor the appropriate D-Link regional support channel for revision-specific firmware and security guidance; do not install firmware intended for a different hardware revision.
Patch, then assume compromise.
No vendor patch or fixed firmware version is confirmed as available. Monitor the applicable D-Link regional support channel for a firmware update or security advisory specific to the DIR-822A hardware revision, and install only firmware intended for that exact revision.
No public exploits tracked yet. Mallory keeps watching.
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
19 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.