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VulnerabilityPublished Updated

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

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in f05b3f4c78370469286879c765f5a1dd39dbcd32 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in f05b3f4c78370469286879c765f5a1dd39dbcd32, ec7d54d8cc1723921d671e3272b427c96366506f, b65289e1c3f352a9f92c6e19713ddd647e033253 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < f05b3f4c78370469286879c765f5a1dd39dbcd32
Fixed in
  • f05b3f4c78370469286879c765f5a1dd39dbcd32
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < ec7d54d8cc1723921d671e3272b427c96366506f
Fixed in
  • ec7d54d8cc1723921d671e3272b427c96366506f
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < b65289e1c3f352a9f92c6e19713ddd647e033253
Fixed in
  • b65289e1c3f352a9f92c6e19713ddd647e033253
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2
Fixed in
  • a0c5fdeb5fa257f8c6d469af266bc087cb5de6a2
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < 1579342d71133da7f00daa02c75cebec7372097b
Fixed in
  • 1579342d71133da7f00daa02c75cebec7372097b
LinuxLinuxAffected
  • ≥ 25b0b9c4e835ffaa65b61c3efe2e28acf84d0259, < 380413cdfd29fb9fa486c82889132b680c4983c5
Fixed in
  • 380413cdfd29fb9fa486c82889132b680c4983c5

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.

References

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