Linux Kernel up to 6.6.106/6.12.47/6.16.7/6.17-rc5 BPF Call bpf_timer_init stack-based overflow

CVSS Meta Temp Score
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CTI Interest Score
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6.6$0-$5k0.00

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 6.6.106/6.12.47/6.16.7/6.17-rc5. This affects the function bpf_timer_init of the component BPF Call Handler. The manipulation results in stack-based overflow. This vulnerability was named CVE-2025-39886. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.106/6.12.47/6.16.7/6.17-rc5. It has been classified as critical. Affected is the function bpf_timer_init of the component BPF Call Handler. The manipulation with an unknown input leads to a stack-based overflow vulnerability. CWE is classifying the issue as CWE-121. A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: bpf: Tell memcg to use allow_spinning=false path in bpf_timer_init() Currently, calling bpf_map_kmalloc_node() from __bpf_async_init() can cause various locking issues; see the following stack trace (edited for style) as one example: ... [10.011566] do_raw_spin_lock.cold [10.011570] try_to_wake_up (5) double-acquiring the same [10.011575] kick_pool rq_lock, causing a hardlockup [10.011579] __queue_work [10.011582] queue_work_on [10.011585] kernfs_notify [10.011589] cgroup_file_notify [10.011593] try_charge_memcg (4) memcg accounting raises an [10.011597] obj_cgroup_charge_pages MEMCG_MAX event [10.011599] obj_cgroup_charge_account [10.011600] __memcg_slab_post_alloc_hook [10.011603] __kmalloc_node_noprof ... [10.011611] bpf_map_kmalloc_node [10.011612] __bpf_async_init [10.011615] bpf_timer_init (3) BPF calls bpf_timer_init() [10.011617] bpf_prog_xxxxxxxxxxxxxxxx_fcg_runnable [10.011619] bpf__sched_ext_ops_runnable [10.011620] enqueue_task_scx (2) BPF runs with rq_lock held [10.011622] enqueue_task [10.011626] ttwu_do_activate [10.011629] sched_ttwu_pending (1) grabs rq_lock ... The above was reproduced on bpf-next (b338cf849ec8) by modifying ./tools/sched_ext/scx_flatcg.bpf.c to call bpf_timer_init() during ops.runnable(), and hacking the memcg accounting code a bit to make a bpf_timer_init() call more likely to raise an MEMCG_MAX event. We have also run into other similar variants (both internally and on bpf-next), including double-acquiring cgroup_file_kn_lock, the same worker_pool::lock, etc. As suggested by Shakeel, fix this by using __GFP_HIGH instead of GFP_ATOMIC in __bpf_async_init(), so that e.g. if try_charge_memcg() raises an MEMCG_MAX event, we call __memcg_memory_event() with @allow_spinning=false and avoid calling cgroup_file_notify() there. Depends on mm patch "memcg: skip cgroup_file_notify if spinning is not allowed": https://lore.kernel.org/bpf/[email protected]/ v0 approach s/bpf_map_kmalloc_node/bpf_mem_alloc/ https://lore.kernel.org/bpf/[email protected]/ v1 approach: https://lore.kernel.org/bpf/[email protected]/

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2025-39886 since 04/16/2025. The exploitability is told to be easy. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 02/16/2026).

The vulnerability scanner Nessus provides a plugin with the ID 265877 (Linux Distros Unpatched Vulnerability : CVE-2025-39886), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.107, 6.12.48, 6.16.8 or 6.17-rc6 eliminates this vulnerability. Applying the patch 449682e76f32601f211816d3e2100bed87e67a4c/cd1fd26bb13473c1734e3026b2b97025a0a4087b/ac70cd446f83ccb25532b343919ab86eacdcd06a/6d78b4473cdb08b74662355a9e8510bde09c511e is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (265877) and CERT Bund (WID-SEC-2025-2107). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Dell Secure Connect Gateway
  • IBM QRadar SIEM
  • Dell NetWorker

Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.8
VulDB Meta Temp Score: 6.6

VulDB Base Score: 8.0
VulDB Temp Score: 7.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.5
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Stack-based overflow
CWE: CWE-121 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 265877
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2025-39886

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.107/6.12.48/6.16.8/6.17-rc6
Patch: 449682e76f32601f211816d3e2100bed87e67a4c/cd1fd26bb13473c1734e3026b2b97025a0a4087b/ac70cd446f83ccb25532b343919ab86eacdcd06a/6d78b4473cdb08b74662355a9e8510bde09c511e

Timelineinfo

04/16/2025 CVE reserved
09/23/2025 +160 days Advisory disclosed
09/23/2025 +0 days VulDB entry created
02/16/2026 +146 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-39886 (🔒)
GCVE (CVE): GCVE-0-2025-39886
GCVE (VulDB): GCVE-100-325608
CERT Bund: WID-SEC-2025-2107 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 09/23/2025 08:38
Updated: 02/16/2026 09:40
Changes: 09/23/2025 08:38 (59), 09/28/2025 18:35 (2), 12/02/2025 05:07 (7), 12/13/2025 10:30 (11), 01/12/2026 09:56 (1), 02/09/2026 08:19 (1), 02/16/2026 09:40 (1)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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