CVE-2025-39848: linux kernel vulnerability

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()").
CVE-2025-39848CVSS 5.5Linux

CVE-2025-39848: linux kernel vulnerability

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()").

CVSS
5.5 MEDIUM
EPSS
4.53%
Known exploited
not in KEV
Product
linux kernel

What is known

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()").

Sources

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