Upstream information
Description
In the Linux kernel, the following vulnerability has been resolved:net/sched: act_mirred: Fix blockcast recursion bypass leading to stack overflow
tcf_mirred_act() checks sched_mirred_nest against MIRRED_NEST_LIMIT (4)
to prevent deep recursion. However, when the action uses blockcast
(tcfm_blockid != 0), the function returns at the tcf_blockcast() call
BEFORE reaching the counter increment. As a result, the recursion
counter never advances and the limit check is entirely bypassed.
When two devices share a TC egress block with a mirred blockcast rule,
a packet egressing on device A is mirrored to device B via blockcast;
device B's egress TC re-enters tcf_mirred_act() via blockcast and
mirrors back to A, creating an unbounded recursion loop:
tcf_mirred_act -> tcf_blockcast -> tcf_mirred_to_dev -> dev_queue_xmit
-> sch_handle_egress -> tcf_classify -> tcf_mirred_act -> (repeat)
This recursion continues until the kernel stack overflows.
The bug is reachable from an unprivileged user via
unshare(CLONE_NEWUSER | CLONE_NEWNET): user namespaces grant
CAP_NET_ADMIN in the new network namespace, which is sufficient to
create dummy devices, attach clsact qdiscs with shared blocks, and
install mirred blockcast filters.
BUG: TASK stack guard page was hit at ffffc90000b7fff8
Oops: stack guard page: 0000 [#1] SMP KASAN NOPTI
CPU: 2 UID: 1000 PID: 169 Comm: poc Not tainted 7.0.0-rc7-next-20260410
RIP: 0010:xas_find+0x17/0x480
Call Trace:
xa_find+0x17b/0x1d0
tcf_mirred_act+0x640/0x1060
tcf_action_exec+0x400/0x530
basic_classify+0x128/0x1d0
tcf_classify+0xd83/0x1150
tc_run+0x328/0x620
__dev_queue_xmit+0x797/0x3100
tcf_mirred_to_dev+0x7b1/0xf70
tcf_mirred_act+0x68a/0x1060
[repeating ~30+ times until stack overflow]
Kernel panic - not syncing: Fatal exception in interrupt
Fix this by incrementing sched_mirred_nest before calling
tcf_blockcast() and decrementing it on return, mirroring the
non-blockcast path. This ensures subsequent recursive entries see the
updated counter and are correctly limited by MIRRED_NEST_LIMIT.
SUSE information
Overall state of this security issue: New
This issue is currently rated as having not set severity.
Note from the SUSE Security Team on the kernel-default package
SUSE will no longer fix all CVEs in the Linux Kernel anymore, but declare some bug classes as won't fix. Please refer to TID 21496 for more details. No SUSE Bugzilla entries cross referenced. No SUSE Security Announcements cross referenced.Status of this issue by product and package
Please note that this evaluation state might be work in progress, incomplete or outdated. Also information for service packs in the LTSS phase is only included for issues meeting the LTSS criteria. If in doubt, feel free to contact us for clarification. The updates are grouped by state of their lifecycle. SUSE product lifecycles are documented on the lifecycle page.
| Product(s) | Source package | State |
|---|---|---|
| Products under general support and receiving all security fixes. | ||
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Desktop 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.0 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.1 | kernel-default | Analysis |
| SUSE Linux Enterprise High Availability Extension 16.1 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.3 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-rt | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Legacy 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Module for Public Cloud 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP7 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 16.1 | kernel-default | Analysis |
| SUSE Linux Enterprise Server 16.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP7 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.0 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.1 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP applications 16.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-default | Analysis |
| SUSE Linux Enterprise Workstation Extension 15 SP7 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-default | Analysis |
| SUSE Linux Micro 6.0 | kernel-source | Analysis |
| SUSE Linux Micro 6.0 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.1 | kernel-default | Analysis |
| SUSE Linux Micro 6.1 | kernel-source | Analysis |
| SUSE Linux Micro 6.1 | kernel-source-rt | Analysis |
| SUSE Linux Micro 6.2 | kernel-default | Analysis |
| SUSE Linux Micro 6.2 | kernel-source | Analysis |
| SUSE Linux Micro Extras 6.0 | kernel-default | Analysis |
| SUSE Linux Micro Extras 6.0 | kernel-source | Analysis |
| SUSE Linux Micro Extras 6.0 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP7 | kernel-source-rt | Analysis |
| openSUSE Leap 16.0 | kernel-source | Analysis |
| Products under Long Term Service Pack support and receiving important and critical security fixes. | ||
| SUSE Linux Enterprise High Performance Computing 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Live Patching 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-default | Analysis |
| SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-default | Analysis |
| SUSE Linux Enterprise Server 12 SP5-LTSS Extended Security | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP5-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP6-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP6-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | kernel-source | Analysis |
| SUSE Manager Proxy 4.3 | kernel-source | Analysis |
| SUSE Manager Proxy LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.3 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server LTS 4.3 | kernel-source | Analysis |
| SUSE Manager Server 4.3 | kernel-source | Analysis |
| SUSE Manager Server LTS 4.3 | kernel-source | Analysis |
| Products past their end of life and not receiving proactive updates anymore. | ||
| SUSE CaaS Platform 4.0 | kernel-source | Analysis |
| SUSE Enterprise Storage 6 | kernel-source | Analysis |
| SUSE Enterprise Storage 7 | kernel-source | Analysis |
| SUSE Enterprise Storage 7.1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP5 | kernel-source | Analysis |
| SUSE Linux Enterprise Desktop 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | kernel-source | Analysis |
| SUSE Linux Enterprise High Performance Computing 15 SP6 | kernel-source | Analysis |
| SUSE Linux Enterprise Micro 5.0 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.1 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-default | Analysis |
| SUSE Linux Enterprise Micro 5.2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Basesystem 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Module for Development Tools 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Real Time 15 SP4 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Real Time 15 SP5 | kernel-source-rt | Analysis |
| SUSE Linux Enterprise Server 11 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 11 SP4-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP1-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP2-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-BCL | kernel-source | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-default | Analysis |
| SUSE Linux Enterprise Server 15 SP3-LTSS | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP1 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP2 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP3 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | kernel-source | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-default | Analysis |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | kernel-source | Analysis |
| SUSE Manager Proxy 4.0 | kernel-source | Analysis |
| SUSE Manager Proxy 4.1 | kernel-source | Analysis |
| SUSE Manager Proxy 4.2 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.0 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.1 | kernel-source | Analysis |
| SUSE Manager Retail Branch Server 4.2 | kernel-source | Analysis |
| SUSE Manager Server 4.0 | kernel-source | Analysis |
| SUSE Manager Server 4.1 | kernel-source | Analysis |
| SUSE Manager Server 4.2 | kernel-source | Analysis |
| SUSE Real Time Module 15 SP4 | kernel-source-rt | Analysis |
| SUSE Real Time Module 15 SP5 | kernel-source-rt | Analysis |
| openSUSE Leap 15.3 | kernel-source | Analysis |
| openSUSE Leap 15.4 | kernel-source | Analysis |
| openSUSE Leap 15.4 | kernel-source-rt | Analysis |
| openSUSE Leap 15.5 | kernel-source | Analysis |
| openSUSE Leap 15.5 | kernel-source-rt | Analysis |
| openSUSE Leap 15.6 | kernel-source | Analysis |
SUSE Timeline for this CVE
CVE page created: Mon Jul 20 11:52:10 2026CVE page last modified: Mon Jul 20 11:52:10 2026