# CVE-2026-46253: pstore/ram: fix buffer overflow in persistent_ram_save_old()

> A heap buffer overflow in the Linux kernel pstore/ram module allows attackers to potentially execute code or cause a denial of service under specific crash and reboot conditions.

- **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:** 3 Jun 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-46253, DEBIAN-CVE-2026-46253, GHSA-rwx9-m3pj-2mv2, ROOT-OS-UBUNTU-2204-CVE-2026-46253, UBUNTU-CVE-2026-46253

## What is CVE-2026-46253?

CVE-2026-46253 is a high-severity memory corruption vulnerability in Linux kernel, published on 3 Jun 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:

pstore/ram: fix buffer overflow in persistent_ram_save_old()

persistent_ram_save_old() can be called multiple times for the same
persistent_ram_zone (e.g., via ramoops_pstore_read -> ramoops_get_next_prz
for PSTORE_TYPE_DMESG records).

Currently, the function only allocates prz->old_log when it is NULL,
but it unconditionally updates prz->old_log_size to the current buffer
size and then performs memcpy_fromio() using this new size. If the
buffer size has grown since the first allocation (which can happen
across different kernel boot cycles), this leads to:

1. A heap buffer overflow (OOB write) in the memcpy_fromio() calls
2. A subsequent OOB read when ramoops_pstore_read() accesses the buffer
   using the incorrect (larger) old_log_size

The KASAN splat would look similar to:
  BUG: KASAN: slab-out-of-bounds in ramoops_pstore_read+0x...
  Read of size N at addr ... by task ...

The conditions are likely extremely hard to hit:

  0. Crash with a ramoops write of less-than-record-max-size bytes.
  1. Reboot: ramoops registers, pstore_get_records(0) reads old crash,
     allocates old_log with size X
  2. Crash handler registered, timer started (if pstore_update_ms >= 0)
  3. Oops happens (non-fatal, system continues)
  4. pstore_dump() writes oops via ramoops_pstore_write() size Y (>X)
  5. pstore_new_entry = 1, pstore_timer_kick() called
  6. System continues running (not a panic oops)
  7. Timer fires after pstore_update_ms milliseconds
  8. pstore_timefunc() → schedule_work() → pstore_dowork() → pstore_get_records(1)
  9. ramoops_get_next_prz() → persistent_ram_save_old()
 10. buffer_size() returns Y, but old_log is X bytes
 11. Y > X: memcpy_fromio() overflows heap

  Requirements:
  - a prior crash record exists that did not fill the record size
    (almost impossible since the crash handler writes as much as it
    can possibly fit into the record, capped by max record size and
    the kmsg buffer almost always exceeds the max record size)
  - pstore_update_ms >= 0 (disabled by default)
  - Non-fatal oops (system survives)

Free and reallocate the buffer when the new size differs from the
previously allocated size. This ensures old_log always has sufficient
space for the data being copied.

Weakness: CWE-787 (Out-of-bounds Write), CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-46253?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-46253?

Apply the vendor's patch.

## Is CVE-2026-46253 being exploited?

There is no known exploitation of CVE-2026-46253 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-2026-46253 and fix it if it is affected.

What it is: CVE-2026-46253 is a high-severity memory corruption vulnerability in Linux kernel, published on 3 Jun 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-2026-46253 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-2026-46253/ (Markdown: https://insights.sbomify.com/CVE-2026-46253/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46253
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46253
- OSV: https://osv.dev/vulnerability/CVE-2026-46253

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46253/
Summaries are generated and may contain mistakes; the official description above is the record.