Answer in brief
CVE-2025-37890 records a Unknown severity 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.
Answer in brief
CVE-2025-37890 records a Unknown severity 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.
A CVSS score is not reported in the current record. 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.
A CVSS score is not reported in the current record. 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.