Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: Restrict...
In the Linux kernel, the following vulnerability has been resolved:
net/sched: Restrict conditions for adding duplicating netems to qdisc tree
netem_enqueue's duplication prevention logic breaks when a netem
resides in a qdisc tree with other netems - this can lead to a
soft lockup and OOM loop in netem_dequeue, as seen in [1].
Ensure that a duplicating netem cannot exist in a tree with other
netems.
Previous approaches suggested in discussions in chronological order:
Track duplication status or ttl in the sk_buff struct. Considered
too specific a use case to extend such a struct, though this would
be a resilient fix and address other previous and potential future
DOS bugs like the one described in loopy fun [2].Restrict netem_enqueue recursion depth like in act_mirred with a
per cpu variable. However, netem_dequeue can call enqueue on its
child, and the depth restriction could be bypassed if the child is a
netem.Use the same approach as in 2, but add metadata in netem_skb_cb
to handle the netem_dequeue case and track a packet's involvement
in duplication. This is an overly complex approach, and Jamal
notes that the skb cb can be overwritten to circumvent this
safeguard.Prevent the addition of a netem to a qdisc tree if its ancestral
path contains a netem. However, filters and actions can cause a
packet to change paths when re-enqueued to the root from netem
duplication, leading us to the current solution: prevent a
duplicating netem from inhabiting the same tree as other netems.
[1] https://lore.kernel.org/netdev/8DuRWwfqjoRDLDmBMlIfbrsZg9Gx50DHJc1ilxsEBNe2D6NMoigR_eIRIG0LOjMc3r10nUUZtArXx4oZBIdUfZQrwjcQhdinnMis_0G7VEk=@willsroot.io/
[2] https://lwn.net/Articles/719297/
Impact
CVE-2025-38553 has a CVSS score of 5.5 (Medium). The vector is requires local access, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2025-38553? CVE-2025-38553 is a medium-severity security vulnerability. No fixed version is listed yet.
- How severe is CVE-2025-38553? CVE-2025-38553 has a CVSS score of 5.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Is there a fix for CVE-2025-38553? No fixed version is listed for CVE-2025-38553 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-38553 exploitable, and should I be worried? Whether CVE-2025-38553 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-38553 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.