CVE-2025-21655

mediumpriority · track · 19EPSS 0.003 · 17 %ileDEEUFRRUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.25% (17th) EPSS

CVSS 4.7 · medium

Is it mine?

96 products

Check your exposure

Who says so?

7 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

In the Linux kernel, the following vulnerability has been resolved: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.

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 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 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

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⚠ sources disagree · medium–high · 4.3–7.8

v3.14.7mediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 1 · impact 3.6

v3.17.8highCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · CISA US

v3.15.5mediumAV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:Hsecondary · Siemens ProductCERT DE

v3.14.3mediumCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-416USprimaryCWE-362USCWE-362USCWE-682US

affected products (96)

Products and version ranges known to be affected.

Debian Linuxall versionscert_bundDEcpe:/o:debian:debian_linux:-
Dell NetWorker vProxy <19.14all versionscert_bundDE
Open Source Linux Kernel <4.19.316all versionscert_bundDE
Open Source Linux Kernel <5.10.198all versionscert_bundDE
Open Source Linux Kernel <5.15.134all versionscert_bundDE
Open Source Linux Kernel <5.4.262all versionscert_bundDE
Open Source Linux Kernel <6.1.125all versionscert_bundDE
Open Source Linux Kernel <6.1.56all versionscert_bundDE
Open Source Linux Kernel <6.12.10all versionscert_bundDE
Open Source Linux Kernel <6.13all versionscert_bundDE
Open Source Linux Kernel <6.4.11all versionscert_bundDE
Open Source Linux Kernel <6.5all versionscert_bundDE
Open Source Linux Kernel <6.6.72all versionscert_bundDE
RESF Rocky Linuxall versionscert_bundDEcpe:/o:resf:rocky_linux:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
Siemens SIMATIC S7 1500 CPUall versionscert_bundDEcpe:/h:siemens:simatic_s7:1500_cpu
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-
Dell Networker≤ vProxy <19.14cert_bundDE
Open Source Linux Kernel< 4.19.316cert_bundDE

showing 20 of 96

advisories (6)

Vendor and ecosystem advisories describing this.

SSA-019113SSA-019113: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.62026-07-14csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 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 fix versions and recommends specific countermeasures for products where fixes are not, or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.6 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 V3.1.6 only; for version V3.1.7 refer to SSA-457936.
SSA-457936SSA-457936: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.72026-10-13csaf · siemens_psirtDE
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
WID-SEC-W-2025-0132Linux Kernel: Schwachstelle ermöglicht Denial of ServiceDeutsch2025-01-20csaf · cert_bundDE
Ein lokaler Angreifer kann eine Schwachstelle in Linux Kernel ausnutzen, um einen Denial of Service Angriff durchzuführen.
ICSA-26-209-04Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-07-14icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.
ICSA-26-295-11Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-10-13icsa · cisa_csaf_otUS
Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.
CERTFR-2026-AVI-1298Multiples vulnérabilités dans les produits SiemensFrançais2026-10-13vendor · certfrFR

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund siemens_psirt cisa_csaf_ot certfr NVD CVE.org MITRE

published 2025-01-20modified 2026-10-15

related (12,251)

Related entries.

ID	severity	EPSS	exploitable	published
CVE-2026-109619US	high8.1OT critical	100.0% (100th)	KEV	2026-10-21
PHP has various global state that temporarily points into request memory. In some scenarios, global state may not be correctly reset, or may be repopulated after being reset. The g…
CVE-2026-109618US	critical9.8OT critical	100.0% (100th)	KEV	2026-10-21
PHP uses longjmp() for out-of-memory (OOM) errors to exit the current context and abort handling of the request. Some contexts may not properly account for this scenario and leave…
CVE-2026-68820US	—OT critical	0.33% (26th)	KEV	2026-08-11
Use after free in Windows Ancillary Function Driver for WinSock allows an authorized attacker to elevate privileges locally.
CVE-2026-5281US	—OT critical	13.5% (96th)	KEV	2026-04-01
Use after free in Dawn in Google Chrome prior to 146.0.7680.178 allowed a remote attacker who had compromised the renderer process to execute arbitrary code via a crafted HTML page…
CVE-2026-2441US	high8.8OT critical	55.0% (99th)	KEV	2026-02-13
Use after free in CSS in Google Chrome prior to 145.0.7632.75 allowed a remote attacker to execute arbitrary code inside a sandbox via a crafted HTML page. (Chromium security sever…

+12246 more

references (19)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan