ring-buffer: Fix subbuf resize race with ring buffer readers (CVE-2026-89771) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-89771

ring-buffer: Fix subbuf resize race with ring buffer readers

Answer in brief

CVE-2026-89771 records a Unknown severity vulnerability in ring-buffer: Fix subbuf resize race with ring buffer readers. 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 11, 2026Updated Sep 11, 2026Source checked Sep 11, 2026First seen by HOL Sep 11, 2026Material review Sep 11, 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	>=f9b94daa542a8d2532f0930f01cd9aec2d19621b <6d666f0b8b36c0765cf19fbe6de5a7ba5a73aad9 \|\| >=f9b94daa542a8d2532f0930f01cd9aec2d19621b <50f4a793c4ff24826efb0ac700989a5063cc53df \|\| >=f9b94daa542a8d2532f0930f01cd9aec2d19621b <0c7c517827a453128a8f58bfd849546a29813b27 \|\| >=f9b94daa542a8d2532f0930f01cd9aec2d19621b <8a5f63637890f03177146efddaba5ec7a1b4d61f	6d666f0b8b36c0765cf19fbe6de5a7ba5a73aad9, 50f4a793c4ff24826efb0ac700989a5063cc53df, 0c7c517827a453128a8f58bfd849546a29813b27, 8a5f63637890f03177146efddaba5ec7a1b4d61f
Linux/Linuxgeneric	6.8	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 6d666f0b8b36c0765cf19fbe6de5a7ba5a73aad9 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 11, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Fix subbuf resize race with ring buffer readers trace_buffer subbuf_size is read lockless in ring_buffer_read_page() and ring_buffer_read_start(), while it can simultaneously be resized with ring_buffer_subbuf_order_set(). Instead of trace_buffer::subbuf_size, use bpage::order in ring_buffer_read_start() and ring_buffer_read_page(). In ring_buffer_read_start(), even with resize_disabled, there is still a possibility of a race with a buffer modification. Hold the trace_buffer mutex to synchronise with any pending ring buffer order modification. trace_buffer::subbuf_size is now actually useless, remove it. Also, create accessors rb_subbuf_capacity() and rb_page_capacity() which return the actual size available for storing events, while rb_subbuf_size() returns the actual subbuf page-size.

Quoted source text, attributed separately from HOL analysis.