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CVE-2026-64543— tipc: fix use-after-free of the discoverer in tipc_disc_rcv()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 4.17版本存在安全漏洞，该漏洞源于tipc组件中的释放后重用问题。

CVSS 7.8 · High EPSS 0.13% · P2

Possible ATT&CK Techniques 1 AI

T1055 · Process Injection

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< 380413cdfd29fb9fa486c82889132b680c4983c5 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< f05b3f4c78370469286879c765f5a1dd39dbcd32 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< 4da2ac7749411971e1b222b992da5a172ce45f98 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< 5e215bf1c47fdddf8203a0fe80a0ed594065f101 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< ec7d54d8cc1723921d671e3272b427c96366506f affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< b65289e1c3f352a9f92c6e19713ddd647e033253 affected
25b0b9c4e835ffaa65b61c3efe2e28acf84d0259< 1579342d71133da7f00daa02c75cebec7372097b affected
… +10 more rows
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I. Basic Information for CVE-2026-64543

Vulnerability Information
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Vulnerability Title
tipc: fix use-after-free of the discoverer in tipc_disc_rcv()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: tipc: fix use-after-free of the discoverer in tipc_disc_rcv() bearer_disable() frees b->disc with tipc_disc_delete()'s plain kfree(), but tipc_disc_rcv() still dereferences b->disc in RX softirq under rcu_read_lock() (tipc_udp_recv -> tipc_rcv -> tipc_disc_rcv). L2 bearers are safe thanks to the synchronize_net() in tipc_disable_l2_media(), but the UDP bearer defers that call to the cleanup_bearer() workqueue, so the discoverer is freed with no grace period: BUG: KASAN: slab-use-after-free in tipc_disc_rcv (net/tipc/discover.c:149) Read of size 8 at addr ffff88802348b728 by task poc_tipc/184 <IRQ> tipc_disc_rcv (net/tipc/discover.c:149) tipc_rcv (net/tipc/node.c:2126) tipc_udp_recv (net/tipc/udp_media.c:391) udp_rcv (net/ipv4/udp.c:2643) ip_local_deliver_finish (net/ipv4/ip_input.c:241) </IRQ> Freed by task 181: kfree (mm/slub.c:6565) bearer_disable (net/tipc/bearer.c:418) tipc_nl_bearer_disable (net/tipc/bearer.c:1001) The bearer is freed with kfree_rcu(); free the discoverer the same way. Add an rcu_head to struct tipc_discoverer and free it and its skb from an RCU callback. Because the RCU callback (tipc_disc_free_rcu) lives in module text, a call_rcu() that is still pending when the tipc module is unloaded would invoke a freed function. Add an rcu_barrier() to tipc_exit() after the bearer subsystem has been torn down, so all pending discoverer callbacks have run before the module text goes away. Reachable from an unprivileged user namespace: the TIPCv2 genl family is netnsok and its bearer commands have no GENL_ADMIN_PERM. Needs CONFIG_TIPC and CONFIG_TIPC_MEDIA_UDP.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 4.17版本存在安全漏洞，该漏洞源于tipc组件中的释放后重用问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259 ~ 380413cdfd29fb9fa486c82889132b680c4983c5 -
Linux Linux 4.17 -

II. Public POCs for CVE-2026-64543

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III. Intelligence Information for CVE-2026-64543

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Patches & Fixes for CVE-2026-64543 (7)

Same Patch Batch · Linux · 2026-07-27 · 26 CVEs total

CVE-2026-64534 9.8 CRITICAL nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path
CVE-2026-64535 9.8 CRITICAL nvmet-tcp: Fix potential UAF when ddgst mismatch
CVE-2026-64541 9.8 CRITICAL net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket
CVE-2026-64551 9.1 CRITICAL sctp: validate STALE_COOKIE cause length before reading staleness
CVE-2026-64555 8.8 HIGH KVM: arm64: nv: Fix SPSR_EL2 restore in kvm_hyp_handle_mops()
CVE-2026-64554 8.8 HIGH netfilter: bridge: fix stale prevhdr pointer in br_ip6_fragment()
CVE-2026-64552 8.4 HIGH virtio-net: fix len check in receive_big()
CVE-2026-64548 8.4 HIGH bpf, sockmap: reject overflowing copy + len in bpf_msg_push_data()
CVE-2026-64536 8.1 HIGH staging: rtl8723bs: fix OOB reads in is_ap_in_tkip() IE loop
CVE-2026-64547 8.1 HIGH net: usb: net1080: validate packet_len before pad-byte access in rx_fixup
CVE-2026-64540 8.1 HIGH usbnet: gl620a: fix out-of-bounds read in genelink_rx_fixup()
CVE-2026-64532 7.8 HIGH fs/ntfs3: bound NTFS_DE view.data_off in UpdateRecordData{Root,Allocation}
CVE-2026-64539 7.8 HIGH Bluetooth: eir: Fix stack OOB write when prepending the Flags AD
CVE-2026-17523 7.8 HIGH can: bcm: switch timer to HRTIMER_MODE_SOFT and remove hrtimer_tasklet
CVE-2026-64533 7.8 HIGH fs/ntfs3: validate lcns_follow in log_replay conversion
CVE-2026-64531 7.8 HIGH net: openvswitch: reject oversized nested action attrs
CVE-2026-64545 7.5 HIGH net, bpf: check master for NULL in xdp_master_redirect()
CVE-2026-64550 7.3 HIGH net: qualcomm: rmnet: validate MAP frame length before ingress parsing
CVE-2026-64546 7.1 HIGH drm/edid: fix OOB read in drm_parse_tiled_block()
CVE-2026-64542 ipv6: ndisc: fix NULL deref in accept_untracked_na()

Showing top 20 of 26 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64543

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