Answer in brief
CVE-2025-37890 records a High severity (CVSS 7.8) vulnerability in net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <273bbcfa53541cde38b2003ad88a59b770306421 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <e0cf8ee23e1915431f262a7b2dee0c7a7d699af0 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <e3e949a39a91d1f829a4890e7dfe9417ac72e4d0 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <8df7d37d626430035b413b97cee18396b3450bef || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <6082a87af4c52f58150d40dec1716011d871ac21 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <2e7093c7a8aba5d4f8809f271488e5babe75e202 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <ac39fd4a757584d78ed062d4f6fd913f83bd98b5 || >=37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea <141d34391abbb315d68556b7c67ad97885407547 | 273bbcfa53541cde38b2003ad88a59b770306421, e0cf8ee23e1915431f262a7b2dee0c7a7d699af0, e3e949a39a91d1f829a4890e7dfe9417ac72e4d0, 8df7d37d626430035b413b97cee18396b3450bef, 6082a87af4c52f58150d40dec1716011d871ac21, 2e7093c7a8aba5d4f8809f271488e5babe75e202, ac39fd4a757584d78ed062d4f6fd913f83bd98b5, 141d34391abbb315d68556b7c67ad97885407547 |
| Linux/Linuxgeneric | 5.0 | Not reported |
Published upstream
May 16, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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/
Quoted source text, attributed separately from HOL analysis.