Linux kernel TIPC: Use-after-free in node lookup by link name
Summary
The TIPC subsystem of the Linux kernel can access a network node that has already been freed. A node is returned from a lookup by link name without a reference, so a netlink handler can use it while a timer frees it for a down peer. A local user with low privileges can trigger this to crash the system or possibly execute code in kernel context. The flaw is only reachable locally and requires a host where TIPC is loaded.
Affected
- Linux kernel from 4.19 onward, before the fixed stable releases listed below
- Mainline 7.3 and later: fix status unknown in the record
Fixed in
- 5.10.273, 5.15.224, 6.1.191, 6.6.160, 6.12.113, 6.18.57, 7.2.11 and later stable releases
- Fixed package versions for your distribution: unknown, check your vendor's tracker
Workaround
- No vendor workaround known.
- If TIPC is not needed, prevent loading the tipc module (modprobe blacklist), after verifying it is not used.
Exploitation
- Not known to be exploited in the wild.
- No public proof-of-concept found; the upstream KASAN report suggests the reporter had a reproducer.
Our recommendation
- Apply the distribution kernel update in the next patch cycle, earlier on multi-user systems, shared hosts and container hosts.
- Check whether the TIPC module is loaded on your servers (lsmod | grep tipc).
- Restrict local shell access to trusted users.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Linux kernel stable commit 1428c5f1 git.kernel.org
- Linux kernel stable commit b60259d4 git.kernel.org
- Linux kernel stable commit f17e7020 git.kernel.org
- OSV entry CVE-2026-99053 osv.dev
- Ubuntu security notice CVE-2026-99053 ubuntu.com
- VulDB CVE-2026-99053 vuldb.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 22:25.
Original description (NVD)
In the Linux kernel, the following vulnerability has been resolved: tipc: hold a reference to nodes found by link name tipc_node_find_by_name() returns a node after dropping its RCU read lock without taking a reference. The LINK_SET, LINK_GET and LINK_RESET_STATS handlers then lock and access the node, racing with timer-driven cleanup of a down peer. Generic netlink serialization does not exclude the node timer. The following interleaving can leave a handler using a freed node: CPU 0: find the node under RCU and release the node read lock CPU 1: tipc_node_timeout() clears the links and unlinks the down node CPU 1: drop the list and timer references, queuing tipc_node_free() CPU 0: leave the RCU read-side critical section CPU 1: complete the grace period and free the node CPU 0: acquire the node lock through the stale pointer LINK_SET also uses the node's media address after releasing the node lock, when passing queued packets to tipc_bearer_xmit(). KASAN on v7.3-rc5 reported: BUG: KASAN: slab-use-after-free in _raw_read_lock_bh Write of size 4 at addr ffff88807e06f008 by task poc/92 Call Trace: _raw_read_lock_bh kernel/locking/spinlock.c:287 tipc_nl_node_set_link net/tipc/node.c:2475 genl_family_rcv_msg_doit net/netlink/genetlink.c:1114 genl_rcv_msg net/netlink/genetlink.c:1209 netlink_rcv_skb net/netlink/af_netlink.c:2575 Allocated by task 0: tipc_node_create net/tipc/node.c:539 tipc_node_check_dest net/tipc/node.c:1196 tipc_disc_rcv net/tipc/discover.c:252 Freed by task 92: kfree mm/slub.c:6801 rcu_core kernel/rcu/tree.c:2919 Last potentially related work creation: __call_rcu_common.constprop.0 kernel/rcu/tree.c:3181 tipc_node_timeout net/tipc/node.c:814 Acquire a reference to the selected node with kref_get_unless_zero() before leaving RCU, returning NULL if the node has already been released. Release that reference on every caller exit after the last node access, including transmission in LINK_SET. Keep the existing link lookup order and locking so concurrent link removal still takes the existing error paths.
NVD references (8)
- https://git.kernel.org/stable/c/1428c5f1d346a2e1ac9156713975a72246957009
- https://git.kernel.org/stable/c/17e73bae400f6a434dc006e3bee92c94cf781954
- https://git.kernel.org/stable/c/384edc67201f8561b7de952647b923f0524b1f36
- https://git.kernel.org/stable/c/3c3b308ee6e25729a6cf09b69cdd0e093220d40b
- https://git.kernel.org/stable/c/5b7e58e8be90f4e8530e7a60372d003dfa7fd666
- https://git.kernel.org/stable/c/92f3b3368722631e933a4db0cf8bd578ed08cd9c
- https://git.kernel.org/stable/c/b60259d4047fbb735476c729dcf9306a038b6110
- https://git.kernel.org/stable/c/f17e70206a1e763fcca2578a8db3c4eed0f843a9
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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