In the Linux kernel, the following vulnerability has been resolved:
tipc: fix u16 MTU truncation in media and bearer MTU validation
Both TIPC_NL_MEDIA_SET and TIPC_NL_BEARER_SET accept user-supplied MTU values but only enforce a minimum bound, not a maximum. When a user sets the MTU to a value exceeding U16_MAX (65535), it passes validation but is silently truncated when assigned to u16 fields l->mtu and l->advertised_mtu in tipc_link_create(). Values like 65536 (0x10000) truncate to 0, causing a division by zero in tipc_link_set_queue_limits() which computes TIPC_MAX_PUBL / (l->mtu / ITEM_SIZE). Other overflowing values (e.g. 65537-131071) produce small incorrect MTU values, resulting in link malfunction behaviors.
Crash stack (triggered as unprivileged user via user namespace):
tipc_link_set_queue_limits net/tipc/link.c:2531 tipc_link_create net/tipc/link.c:520 tipc_node_check_dest net/tipc/node.c:1279 tipc_disc_rcv net/tipc/discover.c:252 tipc_rcv net/tipc/node.c:2129 tipc_udp_recv net/tipc/udp_media.c:392
Two independent paths lack the upper bound check: 1. tipc_udp_mtu_bad() -- called from __tipc_nl_media_set() (MEDIA_SET) 2. inline check in __tipc_nl_bearer_set() at bearer.c:1160 (BEARER_SET)
Fix both by rejecting MTU values above U16_MAX.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Amazon_linux_2023 | — | Upgrade kernel6.12-tools-debuginfoUpgrade bpftool6.12Upgrade python3-perf6.12-debuginfoUpgrade bpftool6.12-debuginfoUpgrade perf6.12Upgrade kernel6.12-modules-extra-commonUpgrade kernel6.12Upgrade kernel6.12-develUpgrade kernel6.12-debuginfo-common-x86_64Upgrade perf6.12-debuginfoUpgrade kernel6.12-debuginfo-common-aarch64Upgrade kernel6.12-modules-extraUpgrade kernel6.12-tools-develUpgrade python3-perf6.12Upgrade kernel6.12-toolsUpgrade kernel6.12-headersUpgrade kernel-livepatch-6.12.103-127.188Upgrade kernel6.12-debuginfo | Sep 1, 2026 | Aug 10, 2026 |
| Debian | — | Upgrade linux-6.12Upgrade linux | Aug 11, 2026 | Aug 11, 2026 |
| Redhat_linux | — | No solution exists | Aug 13, 2026 | Aug 10, 2026 |
| Vmware Photon_os | — | Use 'tdnf update' to upgrade all packages to the latest version. | Aug 17, 2026 | Aug 10, 2026 |
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