Vulnerability in Linux kernel (CVE-2026-98839)
Summary
Vulnerability in Linux kernel (CVE-2026-98839). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
In the Linux kernel, the following vulnerability has been resolved:
vt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection()
In paste_selection(), the loop copies min_t(unsigned int,
vc_sel.buf_len - pasted,tty->receive_room) bytes per iteration into
tty_ldisc_receive_buf() and increments pasted += count.
Because the selection mutex (vc_sel.lock) is dropped inside the loop
Whenever the line discipline buffer fills up and paste_selection()
sleeps on tty->write_wait, a concurrent TIOCLINUX (TIOCL_SETSEL) ioctl
can replace vc_sel.buffer with a shorter selection and reduce
vc_sel.buf_len below pasted.
When paste_selection() resumes, vc_sel.buf_len - pasted underflows as an
unsigned integer to a large positive value, causing
tty_ldisc_receive_buf(ld, vc_sel.buffer + pasted, NULL, count) to read
up to 4094 bytes out-of-bounds past the newly allocated vc_sel.buffer.
Fix this by terminating the loop when pasted >= vc_sel.buf_len.
Kernel stack trace (Linux 7.3.0-rc3):
BUG: KASAN: slab-out-of-bounds in n_tty_receive_buf_common+0xa01/0x1650
Read of size 4094 at addr ffff888101c58010 by task kworker/u17:1/65
Workqueue: events_unbound flush_to_ldisc
Call Trace:
dump_stack_lvl+0x70/0xa0
print_report+0x153/0x4c6
kasan_report+0xf1/0x120
kasan_check_range+0x11c/0x200
__asan_memcpy+0x29/0x70
n_tty_receive_buf_common+0xa01/0x1650
tty_ldisc_receive_buf+0x66/0x110
tty_por…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-98839 has been found in Linux kernel.
Risk of unauthorized operations or information disclosure.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux kernel CVE-2026-98839" on the vendor's site.
CVE-2026-98839 (Linux kernel)
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (unclassified) exists in Linux kernel.
Check the vendor advisory for the affected versions of Linux kernel.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Linux kernel を使っているサービスとバージョンを洗い出す。
-
2Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-98839 linux
References
- web git.kernel.org
- web git.kernel.org
- web git.kernel.org
- web nvd.nist.gov
- web github.com