# CVE-2026-31636: rxrpc: fix RESPONSE authenticator parser OOB read

> A remote attacker can trigger an out-of-bounds read in the Linux kernel's rxrpc module, potentially leaking memory or causing a system crash.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:** 24 Apr 2026
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2026-31636, DEBIAN-CVE-2026-31636, GHSA-mw37-p938-g4hg, UBUNTU-CVE-2026-31636

## What is CVE-2026-31636?

CVE-2026-31636 is a critical memory corruption vulnerability in Linux kernel, published on 24 Apr 2026. 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:

rxrpc: fix RESPONSE authenticator parser OOB read

rxgk_verify_authenticator() copies auth_len bytes into a temporary
buffer and then passes p + auth_len as the parser limit to
rxgk_do_verify_authenticator(). Since p is a __be32 *, that inflates the
parser end pointer by a factor of four and lets malformed RESPONSE
authenticators read past the kmalloc() buffer.

Decoded from the original latest-net reproduction logs with
scripts/decode_stacktrace.sh:

BUG: KASAN: slab-out-of-bounds in rxgk_verify_response()
Call Trace:
 dump_stack_lvl() [lib/dump_stack.c:123]
 print_report() [mm/kasan/report.c:379 mm/kasan/report.c:482]
 kasan_report() [mm/kasan/report.c:597]
 rxgk_verify_response()
   [net/rxrpc/rxgk.c:1103 net/rxrpc/rxgk.c:1167
    net/rxrpc/rxgk.c:1274]
 rxrpc_process_connection()
   [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364
    net/rxrpc/conn_event.c:386]
 process_one_work() [kernel/workqueue.c:3281]
 worker_thread()
   [kernel/workqueue.c:3353 kernel/workqueue.c:3440]
 kthread() [kernel/kthread.c:436]
 ret_from_fork() [arch/x86/kernel/process.c:164]

Allocated by task 54:
 rxgk_verify_response()
   [include/linux/slab.h:954 net/rxrpc/rxgk.c:1155
    net/rxrpc/rxgk.c:1274]
 rxrpc_process_connection()
   [net/rxrpc/conn_event.c:266 net/rxrpc/conn_event.c:364
    net/rxrpc/conn_event.c:386]

Convert the byte count to __be32 units before constructing the parser
limit.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-31636?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31636?

Apply the vendor's patch.

## Is CVE-2026-31636 being exploited?

There is no known exploitation of CVE-2026-31636 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-2026-31636 and fix it if it is affected.

What it is: CVE-2026-31636 is a critical memory corruption vulnerability in Linux kernel, published on 24 Apr 2026. 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-2026-31636 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-2026-31636/ (Markdown: https://insights.sbomify.com/CVE-2026-31636/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31636
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31636
- OSV: https://osv.dev/vulnerability/CVE-2026-31636

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31636/
Summaries are generated and may contain mistakes; the official description above is the record.