Summary
In the Linux kernel, the following vulnerability has been resolved: tipc: do not update mtu if...
In the Linux kernel, the following vulnerability has been resolved:
tipc: do not update mtu if msg_max is too small in mtu negotiation
When doing link mtu negotiation, a malicious peer may send Activate msg
with a very small mtu, e.g. 4 in Shuang's testing, without checking for
the minimum mtu, l->mtu will be set to 4 in tipc_link_proto_rcv(), then
n->links[bearer_id].mtu is set to 4294967228, which is a overflow of
'4 - INT_H_SIZE - EMSG_OVERHEAD' in tipc_link_mss().
With tipc_link.mtu = 4, tipc_link_xmit() kept printing the warning:
tipc: Too large msg, purging xmit list 1 5 0 40 4!
tipc: Too large msg, purging xmit list 1 15 0 60 4!
And with tipc_link_entry.mtu 4294967228, a huge skb was allocated in
named_distribute(), and when purging it in tipc_link_xmit(), a crash
was even caused:
general protection fault, probably for non-canonical address 0x2100001011000dd: 0000 [#1] PREEMPT SMP PTI
CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 6.3.0.neta #19
RIP: 0010:kfree_skb_list_reason+0x7e/0x1f0
Call Trace:
skb_release_data+0xf9/0x1d0
kfree_skb_reason+0x40/0x100
tipc_link_xmit+0x57a/0x740 [tipc]
tipc_node_xmit+0x16c/0x5c0 [tipc]
tipc_named_node_up+0x27f/0x2c0 [tipc]
tipc_node_write_unlock+0x149/0x170 [tipc]
tipc_rcv+0x608/0x740 [tipc]
tipc_udp_recv+0xdc/0x1f0 [tipc]
udp_queue_rcv_one_skb+0x33e/0x620
udp_unicast_rcv_skb.isra.72+0x75/0x90
__udp4_lib_rcv+0x56d/0xc20
ip_protocol_deliver_rcu+0x100/0x2d0
This patch fixes it by checking the new mtu against tipc_bearer_min_mtu(),
and not updating mtu if it is too small.
Impact
CVE-2023-53517 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2023-53517? CVE-2023-53517 is a medium-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2023-53517? CVE-2023-53517 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2023-53517? No fixed version is listed for CVE-2023-53517 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2023-53517 exploitable, and should I be worried? Whether CVE-2023-53517 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-53517 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.