Answer in brief
CVE-2025-37797 records a High severity (CVSS 7.8) vulnerability in net_sched: hfsc: Fix a UAF vulnerability in class handling. 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 | >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <28b09a067831f7317c3841812276022d6c940677 || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <39b9095dd3b55d9b2743df038c32138efa34a9de || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <fcc8ede663569c704fb00a702973bd6c00373283 || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <20d584a33e480ae80d105f43e0e7b56784da41b9 || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <3aa852e3605000d5c47035c3fc3a986d14ccfa9f || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <86cd4641c713455a4f1c8e54c370c598c2b1cee0 || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <bb583c88d23b72d8d16453d24856c99bd93dadf5 || >=21f4d5cc25ec0e6e8eb8420dd2c399e6d2fc7d14 <3df275ef0a6ae181e8428a6589ef5d5231e58b5c | 28b09a067831f7317c3841812276022d6c940677, 39b9095dd3b55d9b2743df038c32138efa34a9de, fcc8ede663569c704fb00a702973bd6c00373283, 20d584a33e480ae80d105f43e0e7b56784da41b9, 3aa852e3605000d5c47035c3fc3a986d14ccfa9f, 86cd4641c713455a4f1c8e54c370c598c2b1cee0, bb583c88d23b72d8d16453d24856c99bd93dadf5, 3df275ef0a6ae181e8428a6589ef5d5231e58b5c |
| Linux/Linuxgeneric | 4.14 | Not reported |
Published upstream
May 2, 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 handling This patch fixes a Use-After-Free vulnerability in the HFSC qdisc class handling. The issue occurs due to a time-of-check/time-of-use condition in hfsc_change_class() when working with certain child qdiscs like netem or codel. The vulnerability works as follows: 1. hfsc_change_class() checks if a class has packets (q.qlen != 0) 2. It then calls qdisc_peek_len(), which for certain qdiscs (e.g., codel, netem) might drop packets and empty the queue 3. The code continues assuming the queue is still non-empty, adding the class to vttree 4. This breaks HFSC scheduler assumptions that only non-empty classes are in vttree 5. Later, when the class is destroyed, this can lead to a Use-After-Free The fix adds a second queue length check after qdisc_peek_len() to verify the queue wasn't emptied.
Quoted source text, attributed separately from HOL analysis.