# CVE-2025-22058: udp: Fix memory accounting leak.

> An integer overflow in Linux kernel UDP memory accounting causes memory leaks and packet drops, leading to denial of service.

- **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:** 16 Apr 2025
- **Updated:** 11 Jun 2026
- **Also known as:** ALSA-2025:14439, AZL-69542, BELL-CVE-2025-22058, DEBIAN-CVE-2025-22058, GHSA-qh2m-xfgm-crh8, RHSA-2025:14439, ROOT-OS-DEBIAN-11-CVE-2025-22058, ROOT-OS-UBUNTU-2204-CVE-2025-22058, ROOT-OS-UBUNTU-2404-CVE-2025-22058, UBUNTU-CVE-2025-22058

## What is CVE-2025-22058?

CVE-2025-22058 is a medium-severity vulnerability in Linux kernel, published on 16 Apr 2025. 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:

udp: Fix memory accounting leak.

Matt Dowling reported a weird UDP memory usage issue.

Under normal operation, the UDP memory usage reported in /proc/net/sockstat
remains close to zero.  However, it occasionally spiked to 524,288 pages
and never dropped.  Moreover, the value doubled when the application was
terminated.  Finally, it caused intermittent packet drops.

We can reproduce the issue with the script below [0]:

  1. /proc/net/sockstat reports 0 pages

    # cat /proc/net/sockstat | grep UDP:
    UDP: inuse 1 mem 0

  2. Run the script till the report reaches 524,288

    # python3 test.py & sleep 5
    # cat /proc/net/sockstat | grep UDP:
    UDP: inuse 3 mem 524288  <-- (INT_MAX + 1) >> PAGE_SHIFT

  3. Kill the socket and confirm the number never drops

    # pkill python3 && sleep 5
    # cat /proc/net/sockstat | grep UDP:
    UDP: inuse 1 mem 524288

  4. (necessary since v6.0) Trigger proto_memory_pcpu_drain()

    # python3 test.py & sleep 1 && pkill python3

  5. The number doubles

    # cat /proc/net/sockstat | grep UDP:
    UDP: inuse 1 mem 1048577

The application set INT_MAX to SO_RCVBUF, which triggered an integer
overflow in udp_rmem_release().

When a socket is close()d, udp_destruct_common() purges its receive
queue and sums up skb->truesize in the queue.  This total is calculated
and stored in a local unsigned integer variable.

The total size is then passed to udp_rmem_release() to adjust memory
accounting.  However, because the function takes a signed integer
argument, the total size can wrap around, causing an overflow.

Then, the released amount is calculated as follows:

  1) Add size to sk->sk_forward_alloc.
  2) Round down sk->sk_forward_alloc to the nearest lower multiple of
      PAGE_SIZE and assign it to amount.
  3) Subtract amount from sk->sk_forward_alloc.
  4) Pass amount >> PAGE_SHIFT to __sk_mem_reduce_allocated().

When the issue occurred, the total in udp_destruct_common() was 2147484480
(INT_MAX + 833), which was cast to -2147482816 in udp_rmem_release().

At 1) sk->sk_forward_alloc is changed from 3264 to -2147479552, and
2) sets -2147479552 to amount.  3) reverts the wraparound, so we don't
see a warning in inet_sock_destruct().  However, udp_memory_allocated
ends up doubling at 4).

Since commit 3cd3399dd7a8 ("net: implement per-cpu reserves for
memory_allocated"), memory usage no longer doubles immediately after
a socket is close()d because __sk_mem_reduce_allocated() caches the
amount in udp_memory_per_cpu_fw_alloc.  However, the next time a UDP
socket receives a packet, the subtraction takes effect, causing UDP
memory usage to double.

This issue makes further memory allocation fail once the socket's
sk->sk_rmem_alloc exceeds net.ipv4.udp_rmem_min, resulting in packet
drops.

To prevent this issue, let's use unsigned int for the calculation and
call sk_forward_alloc_add() only once for the small delta.

Note that first_packet_length() also potentially has the same problem.

[0]:
from socket import *

SO_RCVBUFFORCE = 33
INT_MAX = (2 ** 31) - 1

s = socket(AF_INET, SOCK_DGRAM)
s.bind(('', 0))
s.setsockopt(SOL_SOCKET, SO_RCVBUFFORCE, INT_MAX)

c = socket(AF_INET, SOCK_DGRAM)
c.connect(s.getsockname())

data = b'a' * 100

while True:
    c.send(data)

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

## Which versions are affected by CVE-2025-22058?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kernel-rt` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-core` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-core` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-devel` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-devel` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules-extra` | AlmaLinux:8 | All versions | 4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-core` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-core` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-debuginfo` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-devel` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-kvm` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules-extra` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debuginfo` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debuginfo-common-x86_64` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-devel` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-kvm` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules-extra` | Red Hat:enterprise_linux:8::nfv | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-core` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-core` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-debuginfo` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-devel` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debug-modules-extra` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debuginfo` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-debuginfo-common-x86_64` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-devel` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |
| `kernel-rt-modules-extra` | Red Hat:enterprise_linux:8::realtime | All versions | 0:4.18.0-553.71.1.rt7.412.el8_10 |

Products: Linux kernel.

## How do I fix CVE-2025-22058?

Apply the vendor's patch.

## Is CVE-2025-22058 being exploited?

There is no known exploitation of CVE-2025-22058 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-2025-22058 and fix it if it is affected.

What it is: CVE-2025-22058 is a medium-severity vulnerability in Linux kernel, published on 16 Apr 2025. 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-2025-22058 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-2025-22058/ (Markdown: https://insights.sbomify.com/CVE-2025-22058/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-22058
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-22058
- OSV: https://osv.dev/vulnerability/CVE-2025-22058

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-22058/
Summaries are generated and may contain mistakes; the official description above is the record.