CVE-2025-37890

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Source
https://cve.org/CVERecord?id=CVE-2025-37890
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-37890.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2025-37890
Downstream
Related
Published
2025-05-16T13:01:12.798Z
Modified
2026-03-20T12:42:32.222280Z
Summary
net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc
Details

In the Linux kernel, the following vulnerability has been resolved:

net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc

As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case).

This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case.

[1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37890.json",
    "cna_assigner": "Linux"
}
References

Affected packages

Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Affected ranges

Type
GIT
Repo
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Events
Introduced
37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea
Fixed
273bbcfa53541cde38b2003ad88a59b770306421
Fixed
e0cf8ee23e1915431f262a7b2dee0c7a7d699af0
Fixed
e3e949a39a91d1f829a4890e7dfe9417ac72e4d0
Fixed
8df7d37d626430035b413b97cee18396b3450bef
Fixed
6082a87af4c52f58150d40dec1716011d871ac21
Fixed
2e7093c7a8aba5d4f8809f271488e5babe75e202
Fixed
ac39fd4a757584d78ed062d4f6fd913f83bd98b5
Fixed
141d34391abbb315d68556b7c67ad97885407547

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-37890.json"