CVE-2026-68116
HighCVSS 7.9Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel, a vulnerability in the VXLAN module causes corruption of the MDB source list during a failed replace operation. Due to improper error handling, existing source entries are deleted, leading to incorrect behavior of EXCLUDE and INCLUDE filters, causing unauthorized traffic or blocking of legitimate traffic.
Risk Assessment
The vulnerability can be exploited locally to disrupt VXLAN network operations, violating security policies (allowing traffic that should be blocked or blocking allowed traffic). This may lead to service unavailability or unauthorized access to network resources.
Recommendation
It is recommended to immediately apply the patch provided by the Linux kernel vendor for this vulnerability. Also monitor announcements for new kernel versions and plan urgent system updates.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: vxlan: mdb: Fix source list corruption on a failed replace When replacing the source list of an MDB remote entry, all existing sources are first marked for deletion and vxlan_mdb_remote_srcs_add() is then called to add the new source list. Sources present in the new list have their deletion mark cleared, and any sources left marked afterwards are removed. If vxlan_mdb_remote_srcs_add() fails partway through, its error path deletes all entries on the remote's source list. That rollback is only correct for its other caller, vxlan_mdb_remote_add(), where the remote was just allocated and the list contains solely entries added during the call. On the replace path the list also holds pre-existing sources, so a failed replace tears them down together with their (S, G) forwarding entries instead of leaving the entry unchanged. This is reachable from an existing (*, G) remote. An EXCLUDE filter that loses sources starts forwarding traffic that should be blocked, while an INCLUDE filter that loses sources drops traffic that should be forwarded. Mark entries created during the current pass with a new VXLAN_SGRP_F_NEW flag. On failure, delete only those entries and clear the deletion mark on the pre-existing ones, so a failed replace leaves the source list untouched. Retain the flag until the whole operation succeeds and then clear it. Also stop vxlan_mdb_remote_src_add() from deleting a pre-existing entry it only looked up when adding that entry's forwarding entry fails.