Vulnerability in Linux kernel (CVE-2026-98809)
Summary
Vulnerability in Linux kernel (CVE-2026-98809). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: don't drain cmd_sync backlog on unregister
hci_unregister_dev() disables cmd_work and cmd_timer, then calls
hci_cmd_sync_clear(), whose cancel_work_sync() waits for
hci_cmd_sync_work() to return. That worker dequeues and runs every
entry on cmd_sync_work_list. With cmd_work disabled nothing reaches
the controller, so each queued HCI command waits the full
HCI_CMD_TIMEOUT (2s).
The backlog has no bound. Userspace can keep queuing MGMT commands
such as MGMT_OP_GET_CLOCK_INFO against a controller that doesn't
answer. Closing /dev/vhci then blocks in vhci_release() for
backlog * 2s:
INFO: task syz-executor:5749 blocked for more than 143 seconds.
cancel_work_sync
hci_cmd_sync_clear
hci_unregister_dev
vhci_release
In a local reproduction the backlog held more than 5000 entries,
which comes to hours of hang.
Stop the worker from taking new entries once HCI_UNREGISTER is set,
and wake any request still waiting with -ENODEV before cancelling
the work. The entries left over are destroyed with -ECANCELED by the
existing sweep in hci_cmd_sync_clear(). They stay on the list until
the work has stopped, so hci_cmd_sync_dequeue() and friends still see
them. A callback already running may still issue another command,
which delays unregister by at most one timeout per remaining command,
not by the whole backlog.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-98809 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-98809" on the vendor's site.
CVE-2026-98809 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-98809 linux
References
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com