CVE-2025-21764 | ndisc: use RCU protection in ndisc_alloc_skb()

In the Linux kernel, the following vulnerability has been resolved: ndisc: use RCU protection in ndisc_alloc_skb() ndisc_alloc_skb() can be called without RTNL or RCU being held. Add RCU protection to avoid possible UAF.

Published: 2025-02-26 Last update: 2026-06-17 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-2025-21764 is rated Low Risk (36.1/100): CVSS High severity, with low exploitation likelihood (EPSS 0.23%). 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-2025-21764

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 2026-06-15 0.01% 0.23% +0.21%
2 2026-04-30 0.05% 0.01% -0.04%
3 2026-04-07 — 0.05% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21764

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-21764

GitHub Security Advisory for CVE-2025-21764

GHSA-j8mq-pfgm-36r2 · Severity: high — In the Linux kernel, the following vulnerability has been resolved: ndisc: use RCU protection in...

OS Trackers for CVE-2025-21764

vendor priority summary link
debian not yet assigned CVE-2025-21764 not yet assigned 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-2025-21764
redhat medium — https://access.redhat.com/security/cve/CVE-2025-21764
suse medium — https://www.suse.com/security/cve/CVE-2025-21764/
ubuntu medium CVE-2025-21764 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 189, ignored 154, not-affected 43, needed 20. https://ubuntu.com/security/CVE-2025-21764

Affected software / configurations for CVE-2025-21764

Vendor Product Version Raw CPE
linux linux_kernel >= 3.9, < 5.4.291 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.235 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.179 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.129 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.79 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.16 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.13.4 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:*:*:*:*:*:*

References for CVE-2025-21764

URL Tags
https://git.kernel.org/stable/c/3c2d705f5adf5d860aaef90cb4211c0fde2ba66d Patch
https://git.kernel.org/stable/c/628e6d18930bbd21f2d4562228afe27694f66da9 Patch
https://git.kernel.org/stable/c/96fc896d0e5b37c12808df797397fb16f3080879 Patch
https://git.kernel.org/stable/c/9e0ec817eb41a55327a46cd3ce331a9868d60304 Patch
https://git.kernel.org/stable/c/b870256dd2a5648d5ed2f22316b3ac29a7e5ed63 Patch
https://git.kernel.org/stable/c/bbec88e4108e8d6fb468d3817fa652140a44ff28 Patch
https://git.kernel.org/stable/c/c30893ef3d9cde8e7e8e4fd06b53d2c935bbccb1 Patch
https://git.kernel.org/stable/c/cd1065f92eb7ff21b9ba5308a86f33d1670bf926 Patch
https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
https://cert-portal.siemens.com/productcert/html/ssa-265688.html
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