CVE-2025-21756

highpriority · track · 10EPSS 0.009 · 59 %ileexploit · PoCDEEUFRNLRUUS
grimoire priorityP1 · Urgent
Exploitable?
Public exploit
4 exploits · PoC
Likely / severe?
0.89% (59th) EPSS
CVSS 7.8 · high
Is it mine?
170 products
Check your exposure
Who says so?
9 sources
cnnvd · enisa_euvd · fstec_bdu · osv

EPSS · scored 2026-10-27

In the Linux kernel, the following vulnerability has been resolved: vsock: Keep the binding until socket destruction Preserve sockets bindings; this includes both resulting from an explicit bind() and those implicitly bound through autobind during connect(). Prevents socket unbinding during a transport reassignment, which fixes a use-after-free: 1. vsock_create() (refcnt=1) calls vsock_insert_unbound() (refcnt=2) 2. transport->release() calls vsock_remove_bound() without checking if sk was bound and moved to bound list (refcnt=1) 3. vsock_bind() assumes sk is in unbound list and before __vsock_insert_bound(vsock_bound_sockets()) calls __vsock_remove_bound() which does: list_del_init(&vsk->bound_table); // nop sock_put(&vsk->sk); // refcnt=0 BUG: KASAN: slab-use-after-free in __vsock_bind+0x62e/0x730 Read of size 4 at addr ffff88816b46a74c by task a.out/2057 dump_stack_lvl+0x68/0x90 print_report+0x174/0x4f6 kasan_report+0xb9/0x190 __vsock_bind+0x62e/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Allocated by task 2057: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 __kasan_slab_alloc+0x85/0x90 kmem_cache_alloc_noprof+0x131/0x450 sk_prot_alloc+0x5b/0x220 sk_alloc+0x2c/0x870 __vsock_create.constprop.0+0x2e/0xb60 vsock_create+0xe4/0x420 __sock_create+0x241/0x650 __sys_socket+0xf2/0x1a0 __x64_sys_socket+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e Freed by task 2057: kasan_save_stack+0x1e/0x40 kasan_save_track+0x10/0x30 kasan_save_free_info+0x37/0x60 __kasan_slab_free+0x4b/0x70 kmem_cache_free+0x1a1/0x590 __sk_destruct+0x388/0x5a0 __vsock_bind+0x5e1/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e refcount_t: addition on 0; use-after-free. WARNING: CPU: 7 PID: 2057 at lib/refcount.c:25 refcount_warn_saturate+0xce/0x150 RIP: 0010:refcount_warn_saturate+0xce/0x150 __vsock_bind+0x66d/0x730 vsock_bind+0x97/0xe0 __sys_bind+0x154/0x1f0 __x64_sys_bind+0x6e/0xb0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e refcount_t: underflow; use-after-free. WARNING: CPU: 7 PID: 2057 at lib/refcount.c:28 refcount_warn_saturate+0xee/0x150 RIP: 0010:refcount_warn_saturate+0xee/0x150 vsock_remove_bound+0x187/0x1e0 __vsock_release+0x383/0x4a0 vsock_release+0x90/0x120 __sock_release+0xa3/0x250 sock_close+0x14/0x20 __fput+0x359/0xa80 task_work_run+0x107/0x1d0 do_exit+0x847/0x2560 do_group_exit+0xb8/0x250 __x64_sys_exit_group+0x3a/0x50 x64_sys_call+0xfec/0x14f0 do_syscall_64+0x93/0x1b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

No vendor fix yet; a mitigation is available.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 TM MFP - GNU/Linux subsystemsiemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 TM MFP - GNU/Linux subsystemcisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 TM MFP - GNU/Linux subsystemsiemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 TM MFP - GNU/Linux subsystemcisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot

    Currently no fix is available

02

cvss

Technical severity, 0–10. One row per scoring source.

7.8
010

base score 0–10 · higher = more severe · hover a vector to decode

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · CISA US
v3.17.8highAV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 1.8 · impact 5.9
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 1.8 · impact 5.9
v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · Siemens ProductCERT DE
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: poc · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-20USCWE-20USCWE-416USCWE-416USCWE-416USCWE-416USCWE-416US
05

exploits (4)

Public proof-of-concept and weaponised exploit code.

06

affected products (170)

Products and version ranges known to be affected.

showing 20 of 170
07

advisories (11)

Vendor and ecosystem advisories describing this.

  • NCSC-2025-0187Kwetsbaarheden verholpen in Siemens productenNL2025-06-10csaf · ncsc_nlNL

    Siemens heeft kwetsbaarheden verholpen in diverse producten als RUGGEDCOM, SCALANCE, SIMATIC en Tecnomatix

  • SSA-082556SSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.52025-06-10csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fixes and recommends specific mitigations for products where fixes are not or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1.5 only; for version V3.1.6 refer to SSA-019113.

  • SSA-265688SSA-265688: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.12024-04-09csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1. Siemens has released a new version for SIMATIC S7-1500 TM MFP - GNU/Linux subsystem and recommends to update to the latest version. Siemens is preparing further fixes and recommends specific mitigations for products where fixes are not or not yet available. SIMATIC S7-1500 TM MFP V1.1 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V1.1 only; for version V1.1.1 refer to SSA-784472.

  • SSA-784472SSA-784472: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.12026-10-13csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1. Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.

  • WID-SEC-W-2025-0453Linux Kernel: Mehrere SchwachstellenDeutsch2025-02-26csaf · cert_bundDE

    Ein entfernter Angreifer kann mehrere Schwachstellen im Linux Kernel ausnutzen um die Vertraulichkeit, Integrität und Verfügbarkeit zu gefährden.

  • WID-SEC-W-2025-1439Dell Secure Connect Gateway: Mehrere Schwachstellen ermöglichen nicht spezifizierten AngriffDeutsch2025-06-30csaf · cert_bundDE

    Ein Angreifer kann mehrere Schwachstellen in Dell Secure Connect Gateway ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

  • ICSA-24-102-01Siemens SIMATIC S7-1500 TM MFP2024-04-09icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1. Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.

  • ICSA-25-162-05Siemens SIMATIC S7-1500 CPU family2025-06-10icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommends countermeasures for products where fixes are not, or not yet available.

  • ICSA-26-295-16Siemens SIMATIC S7-1500 TM MFP2026-10-13icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the SIMATIC S7-1500 TM MFP V1.1.1. Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.

  • ASB-A-3963317932025-09-01vendor · osvUS

    In multiple functions of af_vsock.c, there is a possible way to cause a use after free due to a logic error in the code. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.

  • CERTFR-2026-AVI-1298Multiples vulnérabilités dans les produits SiemensFrançais2026-10-13vendor · certfrFR
08

also known as (5)

Other names and identifiers for this entity.

09

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bduosvcert_bundncsc_nlsiemens_psirtcisa_csaf_otcertfrNVDCVE.orgMITRE
published 2025-02-27modified 2026-10-15
10

references (25)

External citations — patches, advisories, analysis.

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