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Fencer Vulns
medium 5.5

CVE-2026-23072 json

l2tp: Fix memleak in l2tp_udp_encap_recv().

published 2026-02-04 9 mo ago modified 2026-06-17 4 mo ago also EUVD-2026-5472

cvss
5.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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

l2tp: Fix memleak in l2tp_udp_encap_recv().

syzbot reported memleak of struct l2tp_session, l2tp_tunnel, sock, etc. [0]

The cited commit moved down the validation of the protocol version in l2tp_udp_encap_recv().

The new place requires an extra error handling to avoid the memleak.

Let's call l2tp_session_put() there.

[0]: BUG: memory leak unreferenced object 0xffff88810a290200 (size 512): comm "syz.0.17", pid 6086, jiffies 4294944299 hex dump (first 32 bytes): 7d eb 04 0c 00 00 00 00 01 00 00 00 00 00 00 00 }............... 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace (crc babb6a4f): kmemleak_alloc_recursive include/linux/kmemleak.h:44 [inline] slab_post_alloc_hook mm/slub.c:4958 [inline] slab_alloc_node mm/slub.c:5263 [inline] __do_kmalloc_node mm/slub.c:5656 [inline] __kmalloc_noprof+0x3e0/0x660 mm/slub.c:5669 kmalloc_noprof include/linux/slab.h:961 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] l2tp_session_create+0x3a/0x3b0 net/l2tp/l2tp_core.c:1778 pppol2tp_connect+0x48b/0x920 net/l2tp/l2tp_ppp.c:755 __sys_connect_file+0x7a/0xb0 net/socket.c:2089 __sys_connect+0xde/0x110 net/socket.c:2108 __do_sys_connect net/socket.c:2114 [inline] __se_sys_connect net/socket.c:2111 [inline] __x64_sys_connect+0x1c/0x30 net/socket.c:2111 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xa4/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Patch / fix

  • Linux Linux 6.12.68, 6.18.8, 6.19
  • linux Debian 13 6.12.69-1
  • linux Debian 14 6.18.8-1

debian advisories DEBIAN-CVE-2026-23072

  • linux-gcp-6.17 Ubuntu 24.04 LTS 6.17.0-1021.24~24.04.1
  • linux-hwe-6.17 Ubuntu 24.04 LTS 6.17.0-41.41~24.04.1
  • linux-oem-6.17 Ubuntu 24.04 LTS 6.17.0-1030.30
  • linux-azure-6.17 Ubuntu 24.04 LTS 6.17.0-1021.21~24.04.1
  • linux-nvidia-6.17 Ubuntu 24.04 LTS 6.17.0-1031.31
  • linux-oracle-6.17 Ubuntu 24.04 LTS 6.17.0-1019.19~24.04.3
  • linux-realtime-6.17 Ubuntu Pro Realtime 24.04 LTS 6.17.0-1018.20~24.04.1

ubuntu advisories UBUNTU-CVE-2026-23072

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-rt Linux Micro 6.2 6.12.0-160000.28.1
  • kernel-64kb Linux Micro 6.2 6.12.0-160000.28.1
  • kernel-source Linux Micro 6.2 6.12.0-160000.28.1
  • kernel-default Linux Micro 6.2 6.12.0-160000.28.1
  • kernel-default-base Linux Micro 6.2 6.12.0-160000.27.1.160000.2.8
  • gdk-pixbuf Linux Micro 6.2 2.42.12-160000.4.1
  • kernel-syms Linux Micro Extras 6.2 6.12.0-160000.28.1
  • kernel-obs-build Linux Micro Extras 6.2 6.12.0-160000.28.1

suse advisories SUSE-SU-2026:21237-1SUSE-SU-2026:21230-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.28.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.28.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.28.1

opensuse advisories openSUSE-SU-2026:20572-1

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-2026-23072 updated cvss 5.5

kernel: l2tp: Fix memleak in l2tp_udp_encap_recv()

  • Red Hat Enterprise Linux 10 kernel
    affected: workaround, no fix available
  • 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
    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

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
  • CWE-401 Missing Release of Memory after Effective Lifetime
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.