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Fencer Vulns
critical 9.8

CVE-2025-38476 in the critical feed json

rpl: Fix use-after-free in rpl_do_srh_inline().

published 2025-07-28 15 mo ago modified 2026-08-05 3 mo ago also EUVD-2025-22886

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

rpl: Fix use-after-free in rpl_do_srh_inline().

Running lwt_dst_cache_ref_loop.sh in selftest with KASAN triggers the splat below [0].

rpl_do_srh_inline() fetches ipv6_hdr(skb) and accesses it after skb_cow_head(), which is illegal as the header could be freed then.

Let's fix it by making oldhdr to a local struct instead of a pointer.

[0]: [root@fedora net]# ./lwt_dst_cache_ref_loop.sh ... TEST: rpl (input) [ 57.631529] ================================================================== BUG: KASAN: slab-use-after-free in rpl_do_srh_inline.isra.0 (net/ipv6/rpl_iptunnel.c:174) Read of size 40 at addr ffff888122bf96d8 by task ping6/1543

CPU: 50 UID: 0 PID: 1543 Comm: ping6 Not tainted 6.16.0-rc5-01302-gfadd1e6231b1 #23 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <IRQ> dump_stack_lvl (lib/dump_stack.c:122) print_report (mm/kasan/report.c:409 mm/kasan/report.c:521) kasan_report (mm/kasan/report.c:221 mm/kasan/report.c:636) kasan_check_range (mm/kasan/generic.c:175 (discriminator 1) mm/kasan/generic.c:189 (discriminator 1)) __asan_memmove (mm/kasan/shadow.c:94 (discriminator 2)) rpl_do_srh_inline.isra.0 (net/ipv6/rpl_iptunnel.c:174) rpl_input (net/ipv6/rpl_iptunnel.c:201 net/ipv6/rpl_iptunnel.c:282) lwtunnel_input (net/core/lwtunnel.c:459) ipv6_rcv (./include/net/dst.h:471 (discriminator 1) ./include/net/dst.h:469 (discriminator 1) net/ipv6/ip6_input.c:79 (discriminator 1) ./include/linux/netfilter.h:317 (discriminator 1) ./include/linux/netfilter.h:311 (discriminator 1) net/ipv6/ip6_input.c:311 (discriminator 1)) __netif_receive_skb_one_core (net/core/dev.c:5967) process_backlog (./include/linux/rcupdate.h:869 net/core/dev.c:6440) __napi_poll.constprop.0 (net/core/dev.c:7452) net_rx_action (net/core/dev.c:7518 net/core/dev.c:7643) handle_softirqs (kernel/softirq.c:579) do_softirq (kernel/softirq.c:480 (discriminator 20)) </IRQ> <TASK> __local_bh_enable_ip (kernel/softirq.c:407) __dev_queue_xmit (net/core/dev.c:4740) ip6_finish_output2 (./include/linux/netdevice.h:3358 ./include/net/neighbour.h:526 ./include/net/neighbour.h:540 net/ipv6/ip6_output.c:141) ip6_finish_output (net/ipv6/ip6_output.c:215 net/ipv6/ip6_output.c:226) ip6_output (./include/linux/netfilter.h:306 net/ipv6/ip6_output.c:248) ip6_send_skb (net/ipv6/ip6_output.c:1983) rawv6_sendmsg (net/ipv6/raw.c:588 net/ipv6/raw.c:918) __sys_sendto (net/socket.c:714 (discriminator 1) net/socket.c:729 (discriminator 1) net/socket.c:2228 (discriminator 1)) __x64_sys_sendto (net/socket.c:2231) do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1)) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130) RIP: 0033:0x7f68cffb2a06 Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08 RSP: 002b:00007ffefb7c53d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 0000564cd69f10a0 RCX: 00007f68cffb2a06 RDX: 0000000000000040 RSI: 0000564cd69f10a4 RDI: 0000000000000003 RBP: 00007ffefb7c53f0 R08: 0000564cd6a032ac R09: 000000000000001c R10: 0000000000000000 R11: 0000000000000202 R12: 0000564cd69f10a4 R13: 0000000000000040 R14: 00007ffefb7c66e0 R15: 0000564cd69f10a0 </TASK>

Allocated by task 1543: kasan_save_stack (mm/kasan/common.c:48) kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1)) __kasan_slab_alloc (mm/kasan/common.c:319 mm/kasan/common.c:345) kmem_cache_alloc_node_noprof (./include/linux/kasan.h:250 mm/slub.c:4148 mm/slub.c:4197 mm/slub.c:4249) kmalloc_reserve (net/core/skbuff.c:581 (discriminator 88)) __alloc_skb (net/core/skbuff.c:669) __ip6_append_data (net/ipv6/ip6_output.c:1672 (discriminator 1)) ip6_ ---truncated---

Patch / fix

  • Linux Linux 5.10.241, 5.15.190, 6.1.147, 6.6.100, 6.12.40, 6.15.8, 6.16
  • linux Debian 12 6.1.147-1
  • linux Debian 13 6.12.41-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38476

  • linux Ubuntu 22.04 LTS 5.15.0-163.173
  • linux Ubuntu 24.04 LTS 6.8.0-100.100
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1097.104
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1097.106
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1093.99
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48

ubuntu advisories UBUNTU-CVE-2025-38476

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-livepatch-MICRO-6-0_Update_6 Linux Micro 6.1, Linux Micro 6.0 11-3.1
  • kernel-livepatch-MICRO-6-0-RT_Update_4 Linux Micro 6.1, Linux Micro 6.0 14-1.1
  • kernel-livepatch-MICRO-6-0_Update_4 Linux Micro 6.1, Linux Micro 6.0 15-1.2
  • kernel-livepatch-MICRO-6-0_Update_5 Linux Micro 6.1, Linux Micro 6.0 13-1.2
  • kernel-livepatch-MICRO-6-0_Update_7 Linux Micro 6.0 10-1.2
  • kernel-livepatch-MICRO-6-0_Update_8 Linux Micro 6.0 10-1.2
  • kernel-livepatch-MICRO-6-0_Update_9 Linux Micro 6.0 10-1.2
  • kernel-livepatch-SLE15-SP7_Update_1 SLE Live Patching 15 SP7 9-150700.2.1

suse advisories SUSE-SU-2026:0284-1SUSE-SU-2026:0283-1SUSE-SU-2026:0274-1SUSE-SU-2026:0270-1SUSE-SU-2026:0269-1SUSE-SU-2026:0262-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.6.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.6.1
  • kernel-kvmsmall openSUSE Leap 16.0 6.12.0-160000.6.1

opensuse advisories openSUSE-SU-2025:20081-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38476 updated

kernel: rpl: Fix use-after-free in rpl_do_srh_inline()

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

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