CVE-2025-38727: Linux kernel · netlink: avoid infinite retry looping in netlink_unicast()
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1095.102~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1095.102~20.04.1, 5.15.0-1098.107~20.04.1, 5.15.0-1095.104~20.04.1 +27
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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.
Patches and advisories
- ubuntu.com/security/notices/USN-7829-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-7933-1 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-gcp-6.11pkg:deb/ubuntu/linux-gcp-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-hwe-6.11pkg:deb/ubuntu/linux-hwe-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-intelpkg:deb/ubuntu/linux-intel?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSlinux-lowlatency-hwe-6.11pkg:deb/ubuntu/linux-lowlatency-hwe-6.11?arch=source&distro=nobleOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: netlink: avoid infinite retry looping in netlink_unicast() netlink_attachskb() checks for the socket's read memory allocation constraints. Firstly, it has: rmem < READ_ONCE(sk->sk_rcvbuf) to check if the just increased rmem value fits into the socket's receive buffer. If not, it proceeds and tries to wait for the memory under: rmem + skb->truesize > READ_ONCE(sk->sk_rcvbuf) The checks don't cover the case when skb->truesize + sk->sk_rmem_alloc is equal to sk->sk_rcvbuf. Thus the function neither successfully accepts these conditions, nor manages to reschedule the task - and is called in retry loop for indefinite time which is caught as: rcu: INFO: rcu_sched self-detected stall on CPU rcu: 0-....: (25999 ticks this GP) idle=ef2/1/0x4000000000000000 softirq=262269/262269 fqs=6212 (t=26000 jiffies g=230833 q=259957) NMI backtrace for cpu 0 CPU: 0 PID: 22 Comm: kauditd Not tainted 5.10.240 #68 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc42 04/01/2014 Call Trace: <IRQ> dump_stack lib/dump_stack.c:120 nmi_cpu_backtrace.cold lib/nmi_backtrace.c:105 nmi_trigger_cpumask_backtrace lib/nmi_backtrace.c:62 rcu_dump_cpu_stacks kernel/rcu/tree_stall.h:335 rcu_sched_clock_irq.cold kernel/rcu/tree.c:2590 update_process_times kernel/time/timer.c:1953 tick_sched_handle kernel/time/tick-sched.c:227 tick_sched_timer kernel/time/tick-sched.c:1399 __hrtimer_run_queues kernel/time/hrtimer.c:1652 hrtimer_interrupt kernel/time/hrtimer.c:1717 __sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1113 asm_call_irq_on_stack arch/x86/entry/entry_64.S:808 </IRQ> netlink_attachskb net/netlink/af_netlink.c:1234 netlink_unicast net/netlink/af_netlink.c:1349 kauditd_send_queue kernel/audit.c:776 kauditd_thread kernel/audit.c:897 kthread kernel/kthread.c:328 ret_from_fork arch/x86/entry/entry_64.S:304 Restore the original behavior of the check which commit in Fixes accidentally missed when restructuring the code. Found by Linux Verification Center (linuxtesting.org).
References
- ubuntu.com/security/CVE-2025-38727 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-38727 (opens in a new tab)
- git.kernel.org/linus/759dfc7d04bab1b0b86113f1164dc1fec192b859 (opens in a new tab)
- git.kernel.org/stable/c/346c820ef5135cf062fa3473da955ef8c5fb6929 (opens in a new tab)
- git.kernel.org/stable/c/44ddd7b1ae0b7edb2c832eb16798c827a05e58f0 (opens in a new tab)
- git.kernel.org/stable/c/47d49fd07f86d1f55ea1083287303d237e9e0922 (opens in a new tab)
- git.kernel.org/stable/c/6bee383ff83352a693d03efdf27cdd80742f71b2 (opens in a new tab)
- git.kernel.org/stable/c/759dfc7d04bab1b0b86113f1164dc1fec192b859 (opens in a new tab)
- git.kernel.org/stable/c/78fcd69d55c5f11d7694c547eca767a1cfd38ec4 (opens in a new tab)
- git.kernel.org/stable/c/d42b71a34f6b8a2d5c53df81169b03b8d8b5cf4e (opens in a new tab)
- git.kernel.org/stable/c/e8edc7de688791a337c068693f22e8d8b869df71 (opens in a new tab)
- git.kernel.org/stable/c/f324959ad47e62e3cadaffa65d3cff790fb48529 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-7829-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-7933-1 (opens in a new tab)