CVE-2025-21994 | ksmbd: fix incorrect validation for num_aces field of smb_acl

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix incorrect validation for num_aces field of smb_acl parse_dcal() validate num_aces to allocate posix_ace_state_array. if (num_aces > ULONG_MAX / sizeof(struct smb_ace *)) It is an incorrect validation that we can create an array of size ULONG_MAX. smb_acl has ->size field to calculate actual number of aces in request buffer size. Use this to check invalid num_aces.

Published: 2025-04-02 Last update: 2025-11-03 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-21994 is rated Low Risk (25.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.03%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-21994

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-11 0.09% 0.03% -0.06%
2 2026-01-27 0.02% 0.09% +0.07%
3 2025-10-29 — 0.02% —

Full EPSS history (11 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21994

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2025-21994

OS Trackers for CVE-2025-21994

vendor priority summary link
debian unimportant CVE-2025-21994 unimportant priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-21994
redhat medium — https://access.redhat.com/security/cve/CVE-2025-21994
suse medium CVE-2025-21994 severity moderate: SUSE including 26 source package names (cluster-md-kmp-default, dlm-kmp-default, …), 264 product×package rows across 51 product lines (SLES-LTSS-TERADATA 15 SP2, SUSE Linux Enterprise High Availability Extension 15 SP7, … (51 product lines)): Known Not Affected 264. https://www.suse.com/security/cve/CVE-2025-21994/
ubuntu medium CVE-2025-21994 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 170, ignored 154, needed 43, not-affected 39. https://ubuntu.com/security/CVE-2025-21994

Affected software / configurations for CVE-2025-21994

Vendor Product Version Raw CPE
linux linux_kernel >= 5.15, < 5.15.180 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.132 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.85 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.21 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.13.9 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:*

References for CVE-2025-21994

cvelogic Threat Intelligence