# CVE-2026-31654: mm/vma: fix memory leak in __mmap_region()

> A memory leak in the Linux kernel's mmap region handling can lead to resource exhaustion and denial of service when specific error paths are triggered.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 24 Apr 2026
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2026-31654, GHSA-cg89-59r4-qfhp, UBUNTU-CVE-2026-31654

## What is CVE-2026-31654?

CVE-2026-31654 is a medium-severity memory corruption vulnerability in Linux kernel, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

mm/vma: fix memory leak in __mmap_region()

commit 605f6586ecf7 ("mm/vma: do not leak memory when .mmap_prepare
swaps the file") handled the success path by skipping get_file() via
file_doesnt_need_get, but missed the error path.

When /dev/zero is mmap'd with MAP_SHARED, mmap_zero_prepare() calls
shmem_zero_setup_desc() which allocates a new shmem file to back the
mapping. If __mmap_new_vma() subsequently fails, this replacement
file is never fput()'d - the original is released by
ksys_mmap_pgoff(), but nobody releases the new one.

Add fput() for the swapped file in the error path.

Reproducible with fault injection.

FAULT_INJECTION: forcing a failure.
name failslab, interval 1, probability 0, space 0, times 1
CPU: 2 UID: 0 PID: 366 Comm: syz.7.14 Not tainted 7.0.0-rc6 #2 PREEMPT(full)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x164/0x1f0
 should_fail_ex+0x525/0x650
 should_failslab+0xdf/0x140
 kmem_cache_alloc_noprof+0x78/0x630
 vm_area_alloc+0x24/0x160
 __mmap_region+0xf6b/0x2660
 mmap_region+0x2eb/0x3a0
 do_mmap+0xc79/0x1240
 vm_mmap_pgoff+0x252/0x4c0
 ksys_mmap_pgoff+0xf8/0x120
 __x64_sys_mmap+0x12a/0x190
 do_syscall_64+0xa9/0x580
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
 </TASK>

kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
BUG: memory leak
unreferenced object 0xffff8881118aca80 (size 360):
  comm "syz.7.14", pid 366, jiffies 4294913255
  hex dump (first 32 bytes):
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
    ff ff ff ff ff ff ff ff c0 28 4d ae ff ff ff ff  .........(M.....
  backtrace (crc db0f53bc):
    kmem_cache_alloc_noprof+0x3ab/0x630
    alloc_empty_file+0x5a/0x1e0
    alloc_file_pseudo+0x135/0x220
    __shmem_file_setup+0x274/0x420
    shmem_zero_setup_desc+0x9c/0x170
    mmap_zero_prepare+0x123/0x140
    __mmap_region+0xdda/0x2660
    mmap_region+0x2eb/0x3a0
    do_mmap+0xc79/0x1240
    vm_mmap_pgoff+0x252/0x4c0
    ksys_mmap_pgoff+0xf8/0x120
    __x64_sys_mmap+0x12a/0x190
    do_syscall_64+0xa9/0x580
    entry_SYSCALL_64_after_hwframe+0x76/0x7e

Found by syzkaller.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2026-31654?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31654?

Apply the vendor's patch.

## Is CVE-2026-31654 being exploited?

There is no known exploitation of CVE-2026-31654 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31654 and fix it if it is affected.

What it is: CVE-2026-31654 is a medium-severity memory corruption vulnerability in Linux kernel, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-31654 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-31654/ (Markdown: https://insights.sbomify.com/CVE-2026-31654/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31654
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31654
- OSV: https://osv.dev/vulnerability/CVE-2026-31654

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31654/
Summaries are generated and may contain mistakes; the official description above is the record.