Kernel-memory overread via selection-length underflow
Published Oct 18, 2026 · Updated Oct 18, 2026
Linux virtual-terminal pasting allows local users to trigger an out-of-bounds kernel read via concurrent selection changes. In paste_selection(), replacing the selection with a shorter buffer while the mutex is released makes vc_sel.buf_len - pasted underflow, passing an oversized read to tty_ldisc_receive_buf(). Virtual-console access and a concurrent selection replacement are required; upstream selection changes require CAP_SYS_ADMIN, and the report demonstrates an overread rather than code execution.
Summary
What happened
Linux virtual-terminal pasting allows local users to trigger an out-of-bounds kernel read via concurrent selection changes. In paste_selection(), replacing the selection with a shorter buffer while the mutex is released makes vc_sel.buf_len - pasted underflow, passing an oversized read to tty_ldisc_receive_buf(). Virtual-console access and a concurrent selection replacement are required; upstream selection changes require CAP_SYS_ADMIN, and the report demonstrates an overread rather than code execution.
The record
- CVE
- CVE-2026-98839
- Published
- Oct 18, 2026
- Updated
- Oct 18, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- Unavailable
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Oct 18, 2026CVE publishedPublication date reported by the CVE source.
- Oct 18, 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=05c508edc9d0b44e4706d3c2cf14ee12aac210d2
- Affected versionversion=3.16.83 <3.17
- Affected versionversion=4.14.173 <4.15
- Affected versionversion=4.19.109 <4.20
- Affected versionversion=4.4.216 <4.5
- Affected versionversion=4.9.216 <4.10
- Affected versionversion=5.4.25 <5.5
- Affected versionversion=54c522782fd11a720f959ee9cb5a15bb9580343d
- Affected versionversion=5.5.9 <5.6
- Affected versionversion=5.6
- Affected versionversion=8c368d36878e2fc99285279fc5e14b3d3cb8947c
- Affected versionversion=9a9c13ad21a8220cb70c9807a920f43520515f94
- Affected versionversion=a4719f6d07b2c63223f7452c435c5f578f105cfe
- Affected versionversion=b4492f1e7456bd162714c0ec2815c2749d930844
- Affected versionversion=e5be0e24ffc7f5783a3864b5b958088ed15be9e8
- Affected versionversion=e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2 <037d7e3ca5c593092f4b0d471eb869a85cbddde0
- Affected versionversion=e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2 <39495ef5d6f8019e62d65807f217a7ca8232727a
- Affected versionversion=e8c75a30a23c6ba63f4ef6895cbf41fd42f21aa2 <619c6d7dd76fff15a9714fbf02ce299b737f01a2
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Activity data is delayed. The latest report is Sep 28, 2026.
Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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