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Linux KernelOperating system · Linux

CVE-2025-37752

HIGH · 7.8 CVSS v3.1 Published 2025-05-01
Fix available
A fix is available. Upgrade to 6.1.135 / 6.6.88 or later.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net_sched: sch_sfq: move the limit validation It is not sufficient to directly validate the limit on the data that the user passes as it can be updated based on how the other parameters are changed. Move the check at the end of the configuration update process to also catch scenarios where the limit is indirectly updated, for example with the following configurations: tc qdisc add dev dummy0 handle 1: root sfq limit 2 flows 1 depth 1 tc qdisc add dev dummy0 handle 1: root sfq limit 2 flows 1 divisor 1 This fixes the following syzkaller reported crash: ------------[ cut here ]------------ UBSAN: array-index-out-of-bounds in net/sched/sch_sfq.c:203:6 index 65535 is out of range for type 'struct sfq_head[128]' CPU: 1 UID: 0 PID: 3037 Comm: syz.2.16 Not tainted 6.14.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x201/0x300 lib/dump_stack.c:120 ubsan_epilogue lib/ubsan.c:231 [inline] __ubsan_handle_out_of_bounds+0xf5/0x120 lib/ubsan.c:429 sfq_link net/sched/sch_sfq.c:203 [inline] sfq_dec+0x53c/0x610 net/sched/sch_sfq.c:231 sfq_dequeue+0x34e/0x8c0 net/sched/sch_sfq.c:493 sfq_reset+0x17/0x60 net/sched/sch_sfq.c:518 qdisc_reset+0x12e/0x600 net/sched/sch_generic.c:1035 tbf_reset+0x41/0x110 net/sched/sch_tbf.c:339 qdisc_reset+0x12e/0x600 net/sched/sch_generic.c:1035 dev_reset_queue+0x100/0x1b0 net/sched/sch_generic.c:1311 netdev_for_each_tx_queue include/linux/netdevice.h:2590 [inline] dev_deactivate_many+0x7e5/0xe70 net/sched/sch_generic.c:1375

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.1.129, < 6.1.135>= 6.6.76, < 6.6.88>= 6.12.13, < 6.12.24>= 6.13.2, < 6.13.12>= 6.14, < 6.14.3= 6.15
Debian LinuxOperating system
Affected:= 11.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.1.135 / 6.6.88 / 6.12.24 or later
Fixed in 6.1.1356.6.886.12.24
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux Kernel 6.1.135+, 6.6.88+, 6.12.24+, or 6.13.12+ (depending on your current branch) | Debian 11 kernel update when available via DSA

  1. 1. Identify the current running kernel version using 'uname -r' or 'cat /proc/version'
  2. 2. Check your distribution's kernel package manager for available updates (e.g., 'apt-cache policy linux-image-*' on Debian, or 'dnf check-update' on RHEL/Fedora)
  3. 3. For Debian 11 (Bullseye): Check for and install any available kernel security updates via 'apt-get update && apt-get upgrade' or wait for DSA (Debian Security Advisory) for this specific CVE
  4. 4. For other Linux distributions: Upgrade to a patched kernel version: 6.1.135+, 6.6.88+, 6.12.24+, or 6.13.12+
  5. 5. Reboot the system to load the fixed kernel
  6. 6. After reboot, verify the new kernel version is loaded with 'uname -r'
  7. 7. Test network queuing functionality with 'tc qdisc show' to ensure sch_sfq operates correctly
Caveat Kernel upgrades carry standard risk; regression testing recommended in non-production environments first. The fix is a targeted bug fix with minimal risk of breaking existing sch_sfq configurations.

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-37752 in production — separate from our analysis above.

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