# CVE-2025-71102: scs: fix a wrong parameter in __scs_magic

CVE-2025-71102 is fixed in linux on 1 platform, first by DEBIAN-CVE-2025-71102, released January 14, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2025-71102
- Priority: Routine
- CVSS: 5.5 (Moderate)
- EPSS: 0.0015
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 14, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-71102

## Description

In the Linux kernel, the following vulnerability has been resolved:  scs: fix a wrong parameter in __scs_magic  __scs_magic() needs a 'void *' variable, but a 'struct task_struct *' is given.  'task_scs(tsk)' is the starting address of the task's shadow call stack, and '__scs_magic(task_scs(tsk))' is the end address of the task's shadow call stack.  Here should be '__scs_magic(task_scs(tsk))'.  The user-visible effect of this bug is that when CONFIG_DEBUG_STACK_USAGE is enabled, the shadow call stack usage checking function (scs_check_usage) would scan an incorrect memory range.  This could lead  1. **Inaccurate stack usage reporting**: The function would calculate    wrong usage statistics for the shadow call stack, potentially showing    incorrect value in kmsg.  2. **Potential kernel crash**: If the value of __scs_magic(tsk)is    greater than that of __scs_magic(task_scs(tsk)), the for loop may    access unmapped memory, potentially causing a kernel panic.  However,    this scenario is unlikely because task_struct is allocated via the slab    allocator (which typically returns lower addresses), while the shadow    call stack returned by task_scs(tsk) is allocated via vmalloc(which    typically returns higher addresses).  However, since this is purely a debugging feature (CONFIG_DEBUG_STACK_USAGE), normal production systems should be not unaffected.  The bug only impacts developers and testers who are actively debugging stack usage with this configuration enabled.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.162-1 | [DEBIAN-CVE-2025-71102](https://patchblox.com/security/data/fix/linux/debian-cve-2025-71102.md) | Jan 14, 2026 |
| Linux | linux Debian 13.5 (trixie) | 6.12.69-1 | [DEBIAN-CVE-2025-71102](https://patchblox.com/security/data/fix/linux/debian-cve-2025-71102.md) | Jan 14, 2026 |
| Linux | linux Debian 14 | 6.18.3-1 | [DEBIAN-CVE-2025-71102](https://patchblox.com/security/data/fix/linux/debian-cve-2025-71102.md) | Jan 14, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.