CVE-2025-39848: debian linux — Fix

Description

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()").

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.12.1 — 5.4.299
linux	linux_kernel	5.5 — 5.10.243
linux	linux_kernel	5.11 — 5.15.192
linux	linux_kernel	5.16 — 6.1.151
linux	linux_kernel	6.2 — 6.6.105
linux	linux_kernel	6.7 — 6.12.46
linux	linux_kernel	6.13 — 6.16.6
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/01a2984cb803f2d487b7074f9718db2bf3531f69 https://git.kernel.org/stable/c/2bd0f67212908243ce88e35bf69fa77155b47b14 https://git.kernel.org/stable/c/42b46684e2c78ee052d8c2ee8d9c2089233c9094 https://git.kernel.org/stable/c/5b079be1b9da49ad88fc304c874d4be7085f7883 https://git.kernel.org/stable/c/7d449b7a6c8ee434d10a483feed7c5c50108cf56 https://git.kernel.org/stable/c/8156210d36a43e76372312c87eb5ea3dbb405a85 https://git.kernel.org/stable/c/89064cf534bea4bb28c83fe6bbb26657b19dd5fe https://git.kernel.org/stable/c/b1c71d674a308d2fbc83efcf88bfc4217a86aa17

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html https://cert-portal.siemens.com/productcert/html/ssa-032379.html

Frequently Asked Questions

What is CVE-2025-39848? +

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()"). It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-39848? +

CVE-2025-39848 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-39848? +

CVE-2025-39848 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-39848? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-39848