# CVE-2023-53186: skbuff: Fix a race between coalescing and releasing SKBs
> A race condition in Linux kernel SKB coalescing can lead to use-after-free or double-free errors, potentially allowing code execution or system crashes.
- **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 15 Sep 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2023-53186, DEBIAN-CVE-2023-53186, GHSA-2937-wfx7-vxfg, RHSA-2025:17896, UBUNTU-CVE-2023-53186
## What is CVE-2023-53186?
CVE-2023-53186 is a high-severity use after free vulnerability in Linux kernel, published on 15 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
### Official description
In the Linux kernel, the following vulnerability has been resolved:
skbuff: Fix a race between coalescing and releasing SKBs
Commit 1effe8ca4e34 ("skbuff: fix coalescing for page_pool fragment
recycling") allowed coalescing to proceed with non page pool page and page
pool page when @from is cloned, i.e.
to->pp_recycle --> false
from->pp_recycle --> true
skb_cloned(from) --> true
However, it actually requires skb_cloned(@from) to hold true until
coalescing finishes in this situation. If the other cloned SKB is
released while the merging is in process, from_shinfo->nr_frags will be
set to 0 toward the end of the function, causing the increment of frag
page _refcount to be unexpectedly skipped resulting in inconsistent
reference counts. Later when SKB(@to) is released, it frees the page
directly even though the page pool page is still in use, leading to
use-after-free or double-free errors. So it should be prohibited.
The double-free error message below prompted us to investigate:
BUG: Bad page state in process swapper/1 pfn:0e0d1
page:00000000c6548b28 refcount:-1 mapcount:0 mapping:0000000000000000
index:0x2 pfn:0xe0d1
flags: 0xfffffc0000000(node=0|zone=1|lastcpupid=0x1fffff)
raw: 000fffffc0000000 0000000000000000 ffffffff00000101 0000000000000000
raw: 0000000000000002 0000000000000000 ffffffffffffffff 0000000000000000
page dumped because: nonzero _refcount
CPU: 1 PID: 0 Comm: swapper/1 Tainted: G E 6.2.0+
Call Trace:
dump_stack_lvl+0x32/0x50
bad_page+0x69/0xf0
free_pcp_prepare+0x260/0x2f0
free_unref_page+0x20/0x1c0
skb_release_data+0x10b/0x1a0
napi_consume_skb+0x56/0x150
net_rx_action+0xf0/0x350
? __napi_schedule+0x79/0x90
__do_softirq+0xc8/0x2b1
__irq_exit_rcu+0xb9/0xf0
common_interrupt+0x82/0xa0
asm_common_interrupt+0x22/0x40
RIP: 0010:default_idle+0xb/0x20
Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)
## Which versions are affected by CVE-2023-53186?
It affects 1 product.
| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kpatch-patch-5_14_0-284_104_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_104_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_104_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-11.el9_2 |
| `kpatch-patch-5_14_0-284_117_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-8.el9_2 |
| `kpatch-patch-5_14_0-284_117_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-8.el9_2 |
| `kpatch-patch-5_14_0-284_117_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-8.el9_2 |
| `kpatch-patch-5_14_0-284_134_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-2.el9_2 |
| `kpatch-patch-5_14_0-284_134_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-2.el9_2 |
| `kpatch-patch-5_14_0-284_134_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-2.el9_2 |
| `kpatch-patch-5_14_0-284_79_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-15.el9_2 |
| `kpatch-patch-5_14_0-284_79_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-15.el9_2 |
| `kpatch-patch-5_14_0-284_79_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-15.el9_2 |
| `kpatch-patch-5_14_0-284_92_1` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-13.el9_2 |
| `kpatch-patch-5_14_0-284_92_1-debuginfo` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-13.el9_2 |
| `kpatch-patch-5_14_0-284_92_1-debugsource` | Red Hat:rhel_e4s:9.2::baseos | All versions | 0:1-13.el9_2 |
Products: Linux kernel.
## How do I fix CVE-2023-53186?
Apply the vendor's patch.
## Is CVE-2023-53186 being exploited?
There is no known exploitation of CVE-2023-53186 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-2023-53186 and fix it if it is affected.
What it is: CVE-2023-53186 is a high-severity use after free vulnerability in Linux kernel, published on 15 Sep 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-53186 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-2023-53186/ (Markdown: https://insights.sbomify.com/CVE-2023-53186/index.md)
```
## Sources
- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-53186
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-53186
- OSV: https://osv.dev/vulnerability/CVE-2023-53186
---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-53186/
Summaries are generated and may contain mistakes; the official description above is the record.