# CVE-2025-68208: bpf: account for current allocated stack depth in widen_imprecise_scalars()

> A flaw in the Linux kernel BPF verifier allows out-of-bounds stack access, potentially enabling code execution or privilege escalation.

- **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:** 16 Dec 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2025-68208, DEBIAN-CVE-2025-68208, GHSA-2x57-vxvc-jh3v, ROOT-OS-DEBIAN-13-CVE-2025-68208, ROOT-OS-UBUNTU-2404-CVE-2025-68208, UBUNTU-CVE-2025-68208

## What is CVE-2025-68208?

CVE-2025-68208 is a high-severity memory corruption vulnerability in Linux, published on 16 Dec 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:

bpf: account for current allocated stack depth in widen_imprecise_scalars()

The usage pattern for widen_imprecise_scalars() looks as follows:

    prev_st = find_prev_entry(env, ...);
    queued_st = push_stack(...);
    widen_imprecise_scalars(env, prev_st, queued_st);

Where prev_st is an ancestor of the queued_st in the explored states
tree. This ancestor is not guaranteed to have same allocated stack
depth as queued_st. E.g. in the following case:

    def main():
      for i in 1..2:
        foo(i)        // same callsite, differnt param

    def foo(i):
      if i == 1:
        use 128 bytes of stack
      iterator based loop

Here, for a second 'foo' call prev_st->allocated_stack is 128,
while queued_st->allocated_stack is much smaller.
widen_imprecise_scalars() needs to take this into account and avoid
accessing bpf_verifier_state->frame[*]->stack out of bounds.

## Which versions are affected by CVE-2025-68208?


## How do I fix CVE-2025-68208?

Apply the vendor's patch.

## Is CVE-2025-68208 being exploited?

There is no known exploitation of CVE-2025-68208 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-68208 and fix it if it is affected.

What it is: CVE-2025-68208 is a high-severity memory corruption vulnerability in Linux, published on 16 Dec 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-2025-68208 in the wild and no public exploit code.

Affected product: Linux. 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-2025-68208/ (Markdown: https://insights.sbomify.com/CVE-2025-68208/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-68208
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-68208
- OSV: https://osv.dev/vulnerability/CVE-2025-68208

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-68208/
Summaries are generated and may contain mistakes; the official description above is the record.