# CVE-2026-31630: rxrpc: proc: size address buffers for %pISpc output

> A stack buffer overflow in the Linux kernel's rxrpc procfs helpers allows attackers to potentially execute code or cause a denial of service via crafted IPv6 addresses.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 21 Oct 2026
- **Also known as:** AZL-83825, BELL-CVE-2026-31630, DEBIAN-CVE-2026-31630, GHSA-9g7x-mw42-qjmh, ROOT-OS-DEBIAN-11-CVE-2026-31630, ROOT-OS-DEBIAN-12-CVE-2026-31630, ROOT-OS-DEBIAN-13-CVE-2026-31630, ROOT-OS-UBUNTU-2204-CVE-2026-31630, ROOT-OS-UBUNTU-2404-CVE-2026-31630, UBUNTU-CVE-2026-31630

## What is CVE-2026-31630?

CVE-2026-31630 is a high-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:

rxrpc: proc: size address buffers for %pISpc output

The AF_RXRPC procfs helpers format local and remote socket addresses into
fixed 50-byte stack buffers with "%pISpc".

That is too small for the longest current-tree IPv6-with-port form the
formatter can produce. In lib/vsprintf.c, the compressed IPv6 path uses a
dotted-quad tail not only for v4mapped addresses, but also for ISATAP
addresses via ipv6_addr_is_isatap().

As a result, a case such as

  [ffff:ffff:ffff:ffff:0:5efe:255.255.255.255]:65535

is possible with the current formatter. That is 50 visible characters, so
51 bytes including the trailing NUL, which does not fit in the existing
char[50] buffers used by net/rxrpc/proc.c.

Size the buffers from the formatter's maximum textual form and switch the
call sites to scnprintf().

Changes since v1:
- correct the changelog to cite the actual maximum current-tree case
  explicitly
- frame the proof around the ISATAP formatting path instead of the earlier
  mapped-v4 example

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-31630?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31630?

Apply the vendor's patch.

## Is CVE-2026-31630 being exploited?

There is no known exploitation of CVE-2026-31630 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-2026-31630 and fix it if it is affected.

What it is: CVE-2026-31630 is a high-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-2026-31630 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-2026-31630/ (Markdown: https://insights.sbomify.com/CVE-2026-31630/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31630
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31630
- OSV: https://osv.dev/vulnerability/CVE-2026-31630

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31630/
Summaries are generated and may contain mistakes; the official description above is the record.