{"id":"CVE-2023-53517","title":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: do not update mtu if msg_max is too small in mtu negotiation\n\nWhen doing link mtu negotiation, a malicious peer may send Activate msg\nwith a very small mtu, e.g","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\ntipc: do not update mtu if msg_max is too small in mtu negotiation\n\nWhen doing link mtu negotiation, a malicious peer may send Activate msg\nwith a very small mtu, e.g. …","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-190"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 4.1, < 5.10.181","linux_kernel >= 5.11, < 5.15.113","linux_kernel >= 5.16, < 6.1.30","linux_kernel >= 6.2, < 6.3.4","linux_kernel = 6.4"],"patched":["linux_kernel 6.3.4"],"published":"2025-10-01","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:17:41.720","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2023-53517","references":[{"url":"https://git.kernel.org/stable/c/1dd7ae5e0cf5a56e513f7ab7ab9570b7496281d2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/259683001d7e879fea4b42084fb6560dd9408a7e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2bd4ff4ffb92113f8acd04dbaed83269172c24b4","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/56077b56cd3fb78e1c8619e29581ba25a5c55e86","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/575e84d90a74c0b091b3417ba763ebb237aa0a8c","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-53517.json"},{"url":"https://access.redhat.com/security/cve/CVE-2023-53517"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2400721"},{"url":"https://www.cve.org/CVERecord?id=CVE-2023-53517"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-53517"},{"url":"https://lore.kernel.org/linux-cve-announce/2025100132-CVE-2023-53517-da77@gregkh/T"},{"url":"https://access.redhat.com/errata/RHSA-2023:7077"}],"tags":["nvd","csaf","vex","red-hat","cve.org","score-dispute"],"epss":0.00305,"epssPercentile":0.23158,"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"total","timestamp":"2026-10-15T21:35:14.831985Z"},"scores":{"nvd":9.8,"vendor":5.5,"cna":9.8},"ingestedAt":"2026-10-15T22:48:25.405Z","slug":"CVE-2023-53517","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\ntipc: do not update mtu if msg_max is too small in mtu negotiation\n\nWhen doing link mtu negotiation, a malicious peer may send Activate msg\nwith a very small mtu, e.g. 4 in Shuang's testing, without checking for\nthe minimum mtu, l->mtu will be set to 4 in tipc_link_proto_rcv(), then\nn->links[bearer_id].mtu is set to 4294967228, which is a overflow of\n'4 - INT_H_SIZE - EMSG_OVERHEAD' in tipc_link_mss().\n\nWith tipc_link.mtu = 4, tipc_link_xmit() kept printing the warning:\n\n tipc: Too large msg, purging xmit list 1 5 0 40 4!\n tipc: Too large msg, purging xmit list 1 15 0 60 4!\n\nAnd with tipc_link_entry.mtu 4294967228, a huge skb was allocated in\nnamed_distribute(), and when purging it in tipc_link_xmit(), a crash\nwas even caused:\n\n  general protection fault, probably for non-canonical address 0x2100001011000dd: 0000 [#1] PREEMPT SMP PTI\n  CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 6.3.0.neta #19\n  RIP: 0010:kfree_skb_list_reason+0x7e/0x1f0\n  Call Trace:\n   <IRQ>\n   skb_release_data+0xf9/0x1d0\n   kfree_skb_reason+0x40/0x100\n   tipc_link_xmit+0x57a/0x740 [tipc]\n   tipc_node_xmit+0x16c/0x5c0 [tipc]\n   tipc_named_node_up+0x27f/0x2c0 [tipc]\n   tipc_node_write_unlock+0x149/0x170 [tipc]\n   tipc_rcv+0x608/0x740 [tipc]\n   tipc_udp_recv+0xdc/0x1f0 [tipc]\n   udp_queue_rcv_one_skb+0x33e/0x620\n   udp_unicast_rcv_skb.isra.72+0x75/0x90\n   __udp4_lib_rcv+0x56d/0xc20\n   ip_protocol_deliver_rcu+0x100/0x2d0\n\nThis patch fixes it by checking the new mtu against tipc_bearer_min_mtu(),\nand not updating mtu if it is too small.\n\n## Affected\n\n- `linux_kernel >= 4.1, < 5.10.181`\n- `linux_kernel >= 5.11, < 5.15.113`\n- `linux_kernel >= 5.16, < 6.1.30`\n- `linux_kernel >= 6.2, < 6.3.4`\n- `linux_kernel = 6.4`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.3.4`\n\n## Vendor advisories\n\n- **RHSA-2023:7077** · Red Hat · fixed in: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat CodeReady Linux Builder (v. 8) · released 2023-11-14 · [advisory](https://access.redhat.com/errata/RHSA-2023:7077)\n- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-16 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-53517.json)","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[{"seq":230077,"id":"CVE-2023-53517","ts":1793124780022,"field":"cvss","old":"5.5","new":"9.8"},{"seq":230076,"id":"CVE-2023-53517","ts":1793124780022,"field":"severity","old":"medium","new":"critical"},{"seq":223739,"id":"CVE-2023-53517","ts":1792238382546,"field":"cvss","old":"9.8","new":"5.5"},{"seq":223738,"id":"CVE-2023-53517","ts":1792238382546,"field":"severity","old":"critical","new":"medium"}]}