CVE-2026-31686 json
mm/kasan: fix double free for kasan pXds
published 2026-04-27 6 mo ago modified 2026-11-06 3 d ago also EUVD-2026-25882
- cvss
- 7.8
- 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 2%
- public exploits
- 0
- none known
Summary
In the Linux kernel, the following vulnerability has been resolved:
mm/kasan: fix double free for kasan pXds
kasan_free_pxd() assumes the page table is always struct page aligned. But that's not always the case for all architectures. E.g. In case of powerpc with 64K pagesize, PUD table (of size 4096) comes from slab cache named pgtable-2^9. Hence instead of page_to_virt(pxd_page()) let's just directly pass the start of the pxd table which is passed as the 1st argument.
This fixes the below double free kasan issue seen with PMEM:
radix-mmu: Mapped 0x0000047d10000000-0x0000047f90000000 with 2.00 MiB pages ================================================================== BUG: KASAN: double-free in kasan_remove_zero_shadow+0x9c4/0xa20 Free of addr c0000003c38e0000 by task ndctl/2164
CPU: 34 UID: 0 PID: 2164 Comm: ndctl Not tainted 6.19.0-rc1-00048-gea1013c15392 #157 VOLUNTARY Hardware name: IBM,9080-HEX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_012) hv:phyp pSeries Call Trace: dump_stack_lvl+0x88/0xc4 (unreliable) print_report+0x214/0x63c kasan_report_invalid_free+0xe4/0x110 check_slab_allocation+0x100/0x150 kmem_cache_free+0x128/0x6e0 kasan_remove_zero_shadow+0x9c4/0xa20 memunmap_pages+0x2b8/0x5c0 devm_action_release+0x54/0x70 release_nodes+0xc8/0x1a0 devres_release_all+0xe0/0x140 device_unbind_cleanup+0x30/0x120 device_release_driver_internal+0x3e4/0x450 unbind_store+0xfc/0x110 drv_attr_store+0x78/0xb0 sysfs_kf_write+0x114/0x140 kernfs_fop_write_iter+0x264/0x3f0 vfs_write+0x3bc/0x7d0 ksys_write+0xa4/0x190 system_call_exception+0x190/0x480 system_call_vectored_common+0x15c/0x2ec ---- interrupt: 3000 at 0x7fff93b3d3f4 NIP: 00007fff93b3d3f4 LR: 00007fff93b3d3f4 CTR: 0000000000000000 REGS: c0000003f1b07e80 TRAP: 3000 Not tainted (6.19.0-rc1-00048-gea1013c15392) MSR: 800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE> CR: 48888208 XER: 00000000 <...> NIP [00007fff93b3d3f4] 0x7fff93b3d3f4 LR [00007fff93b3d3f4] 0x7fff93b3d3f4 ---- interrupt: 3000
The buggy address belongs to the object at c0000003c38e0000 which belongs to the cache pgtable-2^9 of size 4096 The buggy address is located 0 bytes inside of 4096-byte region [c0000003c38e0000, c0000003c38e1000)
The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3c38c head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 memcg:c0000003bfd63e01 flags: 0x63ffff800000040(head|node=6|zone=0|lastcpupid=0x7ffff) page_type: f5(slab) raw: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000 raw: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01 head: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000 head: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01 head: 063ffff800000002 c00c000000f0e301 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected
[ 138.953636] [ T2164] Memory state around the buggy address: [ 138.953643] [ T2164] c0000003c38dff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 138.953652] [ T2164] c0000003c38dff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 138.953661] [ T2164] >c0000003c38e0000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 138.953669] [ T2164] ^ [ 138.953675] [ T2164] c0000003c38e0080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 138.953684] [ T2164] c0000003c38e0100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 138.953692] [ T2164] ================================================================== [ 138.953701] [ T2164] Disabling lock debugging due to kernel taint
Patch / fix
- Linux Linux 5.10.258, 5.15.209, 6.1.175, 6.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0.1, 7.1
- linux Debian 12 6.1.176-1
- linux Debian 13 6.12.85-1
- linux Debian 14 6.19.14-1
debian advisories DEBIAN-CVE-2026-31686
- linux Ubuntu 22.04 LTS 5.15.0-186.196
- linux Ubuntu 24.04 LTS 6.8.0-136.136
- linux Ubuntu 26.04 LTS 7.0.0-27.27
- linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
- linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
- linux-aws Ubuntu 26.04 LTS 7.0.0-1008.8
- linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
- linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
ubuntu advisories UBUNTU-CVE-2026-31686
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-source openSUSE Tumbleweed 7.0.3-1.1
opensuse advisories openSUSE-SU-2026:10703-1
- git.kernel.org/stable/c/7d7b2d5c107a1f6302cf0006d859985e7c3ddd1c commit
- git.kernel.org/stable/c/3298bdf5a878ded06351eb293856fa84e050029e commit
- git.kernel.org/stable/c/2277246ea265cdca64ce6fdea4b26cd6ff0ec4db commit
- git.kernel.org/stable/c/cec74b2ab7dff866b1d77eaa545b9e8fd14a1f87 commit
- git.kernel.org/stable/c/a05f77cb227c39c5069aea6f12762a29d1e6c103 commit
- git.kernel.org/stable/c/f6204f7ff6aff62ce6242a76982c5ba3a9ded707 commit
- git.kernel.org/stable/c/85d98614e089a67dc6faa8ca766fe10a639f82b4 commit
- git.kernel.org/stable/c/b38237a2ea9c6c19836eee2c57037e1f9f103576 commit
- git.kernel.org/stable/c/51d8c78be0c27ddb91bc2c0263941d8b30a47d3b commit
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-2026-31686 updated cvss 6.7
kernel: mm/kasan: fix double free for kasan pXds
-
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 kernelaffected: no fix available “Fix deferred”
-
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 morenot 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
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 3 d ago
Exploit prediction
0.12% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| 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
-
- CWE-415 Double Free
- Technology feeds
References
- git.kernel.org /stable/c/7d7b2d5c107a1f6302cf0006d859985e7c3ddd1c
- git.kernel.org /stable/c/3298bdf5a878ded06351eb293856fa84e050029e
- git.kernel.org /stable/c/2277246ea265cdca64ce6fdea4b26cd6ff0ec4db
-
git.kernel.org
/stable/c/cec74b2ab7dff866b1d77eaa545b9e8fd14a1f87
patch
-
git.kernel.org
/stable/c/a05f77cb227c39c5069aea6f12762a29d1e6c103
patch
-
git.kernel.org
/stable/c/f6204f7ff6aff62ce6242a76982c5ba3a9ded707
patch
-
git.kernel.org
/stable/c/85d98614e089a67dc6faa8ca766fe10a639f82b4
patch
-
git.kernel.org
/stable/c/b38237a2ea9c6c19836eee2c57037e1f9f103576
patch
-
git.kernel.org
/stable/c/51d8c78be0c27ddb91bc2c0263941d8b30a47d3b
patch
Sources
- CVE List CVE-2026-31686
- NVD CVE-2026-31686
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.