Linux Kernel up to 6.17.8 proc_readdir_de use after free

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CTI Interest Score
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7.2$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 6.17.8. This impacts the function proc_readdir_de. Performing a manipulation results in use after free. This vulnerability is cataloged as CVE-2025-40271. Furthermore, there is an exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Linux Kernel up to 6.17.8. This affects the function proc_readdir_de. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: fs/proc: fix uaf in proc_readdir_de() Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access. We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows: 1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3; 2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab; 3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access. CPU 0 | CPU 1 ------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock); [time window] | rb_erase(&root->subdir_node, &parent->subdir); | write_unlock(&proc_subdir_lock); read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF | rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2)

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-40271 since 04/16/2025. The exploitability is told to be easy. Technical details and a public exploit are known.

The exploit is shared for download at exploit-db.com. It is declared as proof-of-concept. The vulnerability scanner Nessus provides a plugin with the ID 278559 (Debian dla-4404 : ata-modules-5.10.0-35-armmp-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.302, 5.10.247, 5.15.197, 6.1.159, 6.6.117, 6.12.59 or 6.17.9 eliminates this vulnerability. Applying the patch 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491/c81d0385500446efe48c305bbb83d47f2ae23a50/4cba73c4c89219beef7685a47374bf88b1022369/6f2482745e510ae1dacc9b090194b9c5f918d774/67272c11f379d9aa5e0f6b16286b9d89b3f76046/623bb26127fb581a741e880e1e1a47d79aecb6f8/03de7ff197a3d0e17d0d5c58fdac99a63cba8110/895b4c0c79b092d732544011c3cecaf7322c36a1 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 Exploit-DB (52550), Tenable (278559), EUVD (EUVD-2025-201584) and CERT Bund (WID-SEC-2025-2756). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • NetApp FAS
  • NetApp AFF
  • SUSE openSUSE
  • RESF Rocky Linux
  • Open Source Linux Kernel
  • Microsoft Azure Linux

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.2

VulDB Base Score: 8.0
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Access: Public
Status: Proof-of-Concept
Download: 🔒

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 278559
Nessus Name: Debian dla-4404 : ata-modules-5.10.0-35-armmp-di - security update

Exploit-DB: 🔒

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.4.302/5.10.247/5.15.197/6.1.159/6.6.117/6.12.59/6.17.9
Patch: 1d1596d68a6f11d28f677eedf6cf5b17dbfeb491/c81d0385500446efe48c305bbb83d47f2ae23a50/4cba73c4c89219beef7685a47374bf88b1022369/6f2482745e510ae1dacc9b090194b9c5f918d774/67272c11f379d9aa5e0f6b16286b9d89b3f76046/623bb26127fb581a741e880e1e1a47d79aecb6f8/03de7ff197a3d0e17d0d5c58fdac99a63cba8110/895b4c0c79b092d732544011c3cecaf7322c36a1

Timelineinfo

04/16/2025 CVE reserved
12/07/2025 +235 days Advisory disclosed
12/07/2025 +0 days VulDB entry created
05/06/2026 +150 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-40271 (🔒)
GCVE (CVE): GCVE-0-2025-40271
GCVE (VulDB): GCVE-100-334629
EUVD: 🔒
CERT Bund: WID-SEC-2025-2756 - Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service

scip Labs: https://www.scip.ch/en/?labs.20161013

Entryinfo

Created: 12/07/2025 08:53
Updated: 05/06/2026 07:48
Changes: 12/07/2025 08:53 (58), 12/07/2025 09:27 (1), 12/09/2025 07:33 (7), 12/13/2025 08:43 (2), 01/04/2026 12:37 (1), 01/22/2026 07:09 (1), 02/23/2026 04:59 (1), 05/06/2026 07:48 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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