CVE-2025-39673
Linux Kernel race condition
- Published5 Sept 2025
Description
In the Linux kernel, the following vulnerability has been resolved: ppp: fix race conditions in ppp_fill_forward_path ppp_fill_forward_path() has two race conditions: 1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic. 2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels. Fix these by using a lockless RCU approach: - Use list_first_or_null_rcu() to safely test and access the first list entry. - Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal. - Check for a NULL pch->chan before dereferencing it.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/0417adf367a0af11adf7ace849af4638cfb573f7
- https://git.kernel.org/stable/c/0f1630be6fcca3f0c63e4b242ad202e5cde28a40
- https://git.kernel.org/stable/c/94731cc551e29511d85aa8dec61a6c071b1f2430
- https://git.kernel.org/stable/c/9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7
- https://git.kernel.org/stable/c/ca18d751bcc9faf5b7e82e9fae1223d103928181
- https://git.kernel.org/stable/c/f97f6475fdcb3c28ff3c55cc4b7bde632119ec08
References
- https://cert-portal.siemens.com/productcert/html/ssa-032379.html
- https://git.kernel.org/stable/c/0417adf367a0af11adf7ace849af4638cfb573f7
- https://git.kernel.org/stable/c/0f1630be6fcca3f0c63e4b242ad202e5cde28a40
- https://git.kernel.org/stable/c/94731cc551e29511d85aa8dec61a6c071b1f2430
- https://git.kernel.org/stable/c/9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7
- https://git.kernel.org/stable/c/ca18d751bcc9faf5b7e82e9fae1223d103928181
- https://git.kernel.org/stable/c/f97f6475fdcb3c28ff3c55cc4b7bde632119ec08
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2025-39673 being actively exploited?
CVE-2025-39673 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.31%.
How severe is CVE-2025-39673?
CVE-2025-39673 has a CVSS 3.1 base score of 9.8, rated critical. EPSS estimates a 0.31% probability of exploitation.
Which products are affected by CVE-2025-39673?
Affected products include Debian Linux, Linux Kernel.
How do I fix CVE-2025-39673?
Upgrade affected software to a fixed version, for example Linux Kernel 5.15.190 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2025-39673 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.