s390/debug: Fix deadlock during unregister

Answer in brief

CVE-2026-90209 records a Unknown severity vulnerability in s390/debug: Fix deadlock during unregister. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=9372a82892c2caa6bccab9a4081166fa769699f8 <a214c3dacc779b2afcb0ac9c8001e45ee4ffb2ed \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <183f8f6d64bb0510070c856b9927618c53014a7b \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <a08b70ed2d1ec907353a72f15163b8e34ff4b2f8 \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <45bb341d1b73eb293e0dd43d9b72bbc8b615d0ba \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <5d83f3faa3fb7f23f298cfd40382611999de5d1d \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <54e1259b75d6402a1d0cfb822b9bb2c507e53dab \|\| >=9372a82892c2caa6bccab9a4081166fa769699f8 <445c31ac638fd1af203d79bdf25fc0cb3149fbbc \|\| c68ba4a708fbd0efdc384cd29250bb292a45e559 \|\| 86f9980909f31ab205323eeeb290fe3cbb4952b4 \|\| fe5793e90d3f572a87ba67fe2f0e1679fdff14f8 \|\| e234f66168f0d50c0d28154fb983a14e85c3c526 \|\| >=5.4.146 <5.5 \|\| >=5.10.65 <5.11 \|\| >=5.13.17 <5.14 \|\| >=5.14.4 <5.15	a214c3dacc779b2afcb0ac9c8001e45ee4ffb2ed, 183f8f6d64bb0510070c856b9927618c53014a7b, a08b70ed2d1ec907353a72f15163b8e34ff4b2f8, 45bb341d1b73eb293e0dd43d9b72bbc8b615d0ba, 5d83f3faa3fb7f23f298cfd40382611999de5d1d, 54e1259b75d6402a1d0cfb822b9bb2c507e53dab, 445c31ac638fd1af203d79bdf25fc0cb3149fbbc, 5.5, 5.11, 5.14, 5.15
Linux/Linuxgeneric	5.15	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to a214c3dacc779b2afcb0ac9c8001e45ee4ffb2ed if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: s390/debug: Fix deadlock during unregister Unregistering an s390dbf debug area while one of the associated debugfs files is being written to can cause a deadlock: $ echo >.../vmur/level $ rmmod vmur =================================================== debugfs write debugfs_file_get() debug_unregister() mutex_lock(debug_mutex) debugfs_remove() wait for debugfs_file_put() debug_file_ops.write() debug_input() mutex_lock(debug_mutex) ==> DEADLOCK Fix this by splitting debug_unregister() into an s390dbf and debugfs part, and running only the s390dbf part with debug_mutex locked.

Quoted source text, attributed separately from HOL analysis.