Local privilege escalation via unchecked QFQ packet length
Published Jul 21, 2023 · Updated Feb 13, 2025
Out-of-bounds write in Linux Kernel 3.8 through 6.5-rc1 allows local users to escalate privileges through the QFQ scheduler. In net/sched/sch_qfq.c, qfq_enqueue passes a size transformed by a TCA_STAB table to qfq_change_agg, which raises lmax without enforcing QFQ_MAX_LMAX and enables heap access beyond the kmalloc-8192 cache. Exploitation requires local low-privileged access to configure a QFQ queuing discipline and crafted size table; successful use can crash the kernel or execute code with elevated privileges.
Summary
What happened
Out-of-bounds write in Linux Kernel 3.8 through 6.5-rc1 allows local users to escalate privileges through the QFQ scheduler. In net/sched/sch_qfq.c, qfq_enqueue passes a size transformed by a TCA_STAB table to qfq_change_agg, which raises lmax without enforcing QFQ_MAX_LMAX and enables heap access beyond the kmalloc-8192 cache. Exploitation requires local low-privileged access to configure a QFQ queuing discipline and crafted size table; successful use can crash the kernel or execute code with elevated privileges.
The record
- CVE
- CVE-2023-3611
- Published
- Jul 21, 2023
- Updated
- Feb 13, 2025
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-787, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jul 21, 2023CVE publishedPublication date reported by the CVE source.
- Feb 13, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=3.8 <6.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Upstream QFQ reproduction sequenceproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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