Kernel memory corruption via exec signal-queue race
Published Oct 6, 2026 · Updated Oct 6, 2026
A signal-queue use-after-free in Linux kernel 6.15 allows local users to corrupt kernel memory during a non-leader thread's exec. During signal-queue flushing, posixtimer_send_sigqueue() can requeue an entry whose list links are being changed, leaving a pointer to a timer freed through RCU. The race requires a blocked thread-directed timer signal, concurrent timer expiry during non-leader exec, and later signal activity; the demonstrated result is a kernel use-after-free write.
Summary
What happened
A signal-queue use-after-free in Linux kernel 6.15 allows local users to corrupt kernel memory during a non-leader thread's exec. During signal-queue flushing, posixtimer_send_sigqueue() can requeue an entry whose list links are being changed, leaving a pointer to a timer freed through RCU. The race requires a blocked thread-directed timer signal, concurrent timer expiry during non-leader exec, and later signal activity; the demonstrated result is a kernel use-after-free write.
The record
- CVE
- CVE-2026-98256
- Published
- Oct 6, 2026
- Updated
- Oct 6, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 6, 2026CVE publishedPublication date reported by the CVE source.
- Oct 6, 2026Record 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=6.15
- Affected versionversion=fb3bbcfe344e64a46574a638b051ffd78762c12d <621c365739828900f32a0c1cdfe5387528a62176
- Affected versionversion=fb3bbcfe344e64a46574a638b051ffd78762c12d <934bd95f1a6404dbb845951b823547abab05a649
- Affected versionversion=fb3bbcfe344e64a46574a638b051ffd78762c12d <d2710c8d938ae6a825a6463158e6e6f31eac792a
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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.
Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
No sourced classifications are available.
Public exploit references
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Technologies
Your stack
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Your stack
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