---
id: "CVE-2026-98449"
kind: "vulnerability"
aliases: ["CVE-2026-98449"]
title: "Linux kernel SMB client: double credit decrement on failed compound send"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["cifs", "kernel", "linux", "runtime", "smb"]
not_affected_if: []
published_at: "2026-10-18T16:16:55+00:00"
first_seen_at: "2026-10-23T21:57:15+00:00"
updated_at: "2026-10-25T05:27:25+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98449", "first_seen_at": "2026-10-23T21:57:15+00:00"}]
---

# Linux kernel SMB client: double credit decrement on failed compound send

When a compound SMB request fails to send, the Linux kernel's CIFS client leaves its request entries queued while reconnecting, so credits are returned twice. The result is a kernel warning (WARN) during SMB2 negotiation, which the sources describe as hit by syzbot.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-23T21:57:15+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-98449

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

smb: client: delete compound mids on send failure before unlock

When sending a compound request fails, smb_send_rqst() kicks off a
reconnect. compound_send_recv() still has those mids on pending_mid_q,
but it unlocks the server without removing them first.

During reconnect, cifs_abort_connection() walks pending_mid_q and runs
each mid callback. With no response yet, those callbacks return credits
and drop in_flight. Then compound_send_recv()'s send-error path returns
the same credits again. in_flight ends up decremented twice and
smb2_add_credits() WARNs.

syzbot hits this during SMB2_negotiate when the socket send fails.

cifs_call_async() already calls delete_mid() before unlock on send
failure. Do the same for compound chains and set cancelled_mid[] so the
out: path does not delete them again.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_