CVE-2025-39848 | ax25: properly unshare skbs in ax25_kiss_rcv()

In the Linux kernel, the following vulnerability has been resolved: ax25: properly unshare skbs in ax25_kiss_rcv() Bernard Pidoux reported a regression apparently caused by commit c353e8983e0d ("net: introduce per netns packet chains"). skb->dev becomes NULL and we crash in __netif_receive_skb_core(). Before above commit, different kind of bugs or corruptions could happen without a major crash. But the root cause is that ax25_kiss_rcv() can queue/mangle input skb without checking if this skb is shared or not. Many thanks to Bernard Pidoux for his help, diagnosis and tests. We had a similar issue years ago fixed with commit 7aaed57c5c28 ("phonet: properly unshare skbs in phonet_rcv()").

Published: 2025-09-19 Last update: 2026-05-12 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-2025-39848 is rated Low Risk (23.6/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). 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-2025-39848

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 2026-01-21 0.06% 0.02% -0.04%
2 2026-01-19 0.02% 0.06% +0.04%
3 2025-09-20 — 0.02% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-39848

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-2025-39848

GitHub Security Advisory for CVE-2025-39848

GHSA-c6g6-j52p-pg8h · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: ax25: properly unshare skbs...

OS Trackers for CVE-2025-39848

vendor priority summary link
debian not yet assigned CVE-2025-39848 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-2025-39848
redhat — — https://access.redhat.com/security/cve/CVE-2025-39848
suse medium CVE-2025-39848 severity moderate: SUSE including 469 source package names (2.1.3-6.80:kernel-default-base-6.4.0-35.1.21.12, 2.1.3-7.57:kernel-default-6.4.0-35.1, …), 1064 product×package rows across 212 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (212 product lines)): Fixed 619, Known Affected 231, Known Not Affected 193, First Fixed 21. https://www.suse.com/security/cve/CVE-2025-39848/
ubuntu medium CVE-2025-39848 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1414 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): DNE 1017, ignored 180, released 149, needed 47, not-affected 17, needs-triage 2, pending 2. https://ubuntu.com/security/CVE-2025-39848

Affected software / configurations for CVE-2025-39848

Vendor Product Version Raw CPE
linux linux_kernel >= 2.6.12.1, < 5.4.299 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5, < 5.10.243 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.192 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.151 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.105 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.46 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.16.6 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 2.6.12 cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*
linux linux_kernel 2.6.12 cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*
linux linux_kernel 2.6.12 cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*
linux linux_kernel 2.6.12 cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*
linux linux_kernel 2.6.12 cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*
linux linux_kernel 6.17 cpe:2.3:o:linux:linux_kernel:6.17:rc1:*:*:*:*:*:*
linux linux_kernel 6.17 cpe:2.3:o:linux:linux_kernel:6.17:rc2:*:*:*:*:*:*
linux linux_kernel 6.17 cpe:2.3:o:linux:linux_kernel:6.17:rc3:*:*:*:*:*:*
linux linux_kernel 6.17 cpe:2.3:o:linux:linux_kernel:6.17:rc4:*:*:*:*:*:*
debian debian_linux 11.0 cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

References for CVE-2025-39848

URL Tags
https://git.kernel.org/stable/c/01a2984cb803f2d487b7074f9718db2bf3531f69 Patch
https://git.kernel.org/stable/c/2bd0f67212908243ce88e35bf69fa77155b47b14 Patch
https://git.kernel.org/stable/c/42b46684e2c78ee052d8c2ee8d9c2089233c9094 Patch
https://git.kernel.org/stable/c/5b079be1b9da49ad88fc304c874d4be7085f7883 Patch
https://git.kernel.org/stable/c/7d449b7a6c8ee434d10a483feed7c5c50108cf56 Patch
https://git.kernel.org/stable/c/8156210d36a43e76372312c87eb5ea3dbb405a85 Patch
https://git.kernel.org/stable/c/89064cf534bea4bb28c83fe6bbb26657b19dd5fe Patch
https://git.kernel.org/stable/c/b1c71d674a308d2fbc83efcf88bfc4217a86aa17 Patch
https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing List Third Party Advisory
https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html Mailing List Third Party Advisory
https://cert-portal.siemens.com/productcert/html/ssa-032379.html
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