btrfs: lzo: reject compressed segment that overflows the compressed input
CVE-2026-80631 · published 28 Aug 2026
How serious is it
- Severity: high, CVSS score 7.5 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-80631?
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Who is affected
- Linux Linux: a6e66e6f8c1b685e11b778bef614480a9c1a5278 to < d9b17f9ce67d00e48fab62dcae197612a58f625f, a6e66e6f8c1b685e11b778bef614480a9c1a5278 to < 1c48c8c807e49ac4f72819a89035fb8d2d094015, a6e66e6f8c1b685e11b778bef614480a9c1a5278 to < be7fb59512ffc2da5d98214a00117dfe9eccab78, a6e66e6f8c1b685e11b778bef614480a9c1a5278 to < 1641d058adfbd50cf95d54581ed5d142ee82c07f
- Linux Linux: 5.15
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
btrfs: lzo: reject compressed segment that overflows the compressed input
lzo_decompress_bio() validates each on-disk segment length seg_len only
against the workspace cbuf size, not against the compressed input size
(compressed_len, the total folio bytes of the bio). A crafted extent can
carry a segment whose seg_len passes the cbuf check but runs past the end
of the bio, so copy_compressed_segment() walks off the last folio:
get_current_folio() then returns the NULL folio from bio_next_folio(), and
with CONFIG_BTRFS_ASSERT disabled (default) folio_size(NULL) faults.
BUG: KASAN: null-ptr-deref in lzo_decompress_bio (fs/btrfs/lzo.c:383)
Read of size 8 at addr 0000000000000000 by task kworker/u8:1/29
Workqueue: btrfs-endio simple_end_io_work
kasan_report (mm/kasan/report.c:590)
lzo_decompress_bio (fs/btrfs/lzo.c:383)
end_bbio_compressed_read (fs/btrfs/compression.c:1065)
btrfs_bio_end_io (fs/btrfs/bio.c:135)
btrfs_check_read_bio (fs/btrfs/bio.c:180 fs/btrfs/bio.c:285)
simple_end_io_work
process_one_work
worker_thread
Reject any segment whose payload would extend beyond compressed_len before
copying it, treating it as corruption like the other on-disk validation
failures in this function.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/d9b17f9ce67d00e48fab62dcae197612a58f625f
- git.kernel.org/stable/c/1c48c8c807e49ac4f72819a89035fb8d2d094015
- git.kernel.org/stable/c/be7fb59512ffc2da5d98214a00117dfe9eccab78
- git.kernel.org/stable/c/1641d058adfbd50cf95d54581ed5d142ee82c07f
- git.kernel.org/stable/c/b0d27d43791b7a3057c3c4aedf9b4aa033d37c46
Merged from CVE List. Last updated 26 Oct 2026. All vulnerabilities · RSS · JSON