CVE-2025-39848

ax25: properly unshare skbs in ax25_kiss_rcv()

MEDIUM
5.5
CVSS Score
Published: September 19, 2025 at 03:26 PM UTC
Updated: October 19, 2026 at 09:10 PM UTC
3 products affected across 3 vendorsLinux KernelDebian LinuxSIMATIC CN 4100

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Severity
MEDIUM5.5
Exploit prediction
EPSS 0.2%

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()").

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

2.6.12.1 ≤ v < 5.4.2995.11 ≤ v < 5.15.1925.16 ≤ v < 6.1.1515.5 ≤ v < 5.10.2436.13 ≤ v < 6.16.66.2 ≤ v < 6.6.1056.7 ≤ v < 6.12.461da177e4c3f41524e886b7f1b8a0c1fc7321cac22.6.122.6.12 rc22.6.12 rc32.6.12 rc42.6.12 rc56.176.17 rc16.17 rc26.17 rc36.17 rc4
Vendor states this is fixed in 01a2984cb803f2d487b7074f9718db2bf3531f69 (fixed)
Vendor states this is fixed in 2bd0f67212908243ce88e35bf69fa77155b47b14 (fixed)
Vendor states this is fixed in 42b46684e2c78ee052d8c2ee8d9c2089233c9094 (fixed)
Vendor states this is fixed in 5b079be1b9da49ad88fc304c874d4be7085f7883 (fixed)
Vendor states this is fixed in 7d449b7a6c8ee434d10a483feed7c5c50108cf56 (fixed)
Vendor states this is fixed in 8156210d36a43e76372312c87eb5ea3dbb405a85 (fixed)
Vendor states this is fixed in 89064cf534bea4bb28c83fe6bbb26657b19dd5fe (fixed)
Vendor states this is fixed in b1c71d674a308d2fbc83efcf88bfc4217a86aa17 (fixed)
Vendor states this is fixed in 2.6.12 (unaffected)
Vendor states this is fixed in 5.10.243 (unaffected)
Vendor states this is fixed in 5.15.192 (unaffected)
Vendor states this is fixed in 5.4.299 (unaffected)
Vendor states this is fixed in 6.1.151 (unaffected)
Vendor states this is fixed in 6.12.46 (unaffected)
Vendor states this is fixed in 6.16.6 (unaffected)
Vendor states this is fixed in 6.17 (unaffected)
Vendor states this is fixed in 6.6.105 (unaffected)
v < V5.0
Affected range stops below V5.0, so it looks safe — our inference, not a vendor statement

CVSS

Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-401

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