CVE-2025-40100

UNRATEDCVSS · not yet scored
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS v2: —Exploit: None knownExposed: 0

A fix is available — apply it.

In the Linux kernel, the following vulnerability has been resolved:

btrfs: do not assert we found block group item when creating free space tree

Currently, when building a free space tree at populate_free_space_tree(), if we are not using the block group tree feature, we always expect to find block group items (either extent items or a block group item with key type BTRFS_BLOCK_GROUP_ITEM_KEY) when we search the extent tree with btrfs_search_slot_for_read(), so we assert that we found an item. However this expectation is wrong since we can have a new block group created in the current transaction which is still empty and for which we still have not added the block group's item to the extent tree, in which case we do not have any items in the extent tree associated to the block group.

The insertion of a new block group's block group item in the extent tree happens at btrfs_create_pending_block_groups() when it calls the helper insert_block_group_item(). This typically is done when a transaction handle is released, committed or when running delayed refs (either as part of a transaction commit or when serving tickets for space reservation if we are low on free space).

So remove the assertion at populate_free_space_tree() even when the block group tree feature is not enabled and update the comment to mention this case.

Syzbot reported this with the following stack trace:

BTRFS info (device loop3 state M): rebuilding free space tree assertion failed: ret == 0 :: 0, in fs/btrfs/free-space-tree.c:1115 ------------[ cut here ]------------ kernel BUG at fs/btrfs/free-space-tree.c:1115! Oops: invalid opcode: 0000 [#1] SMP KASAN PTI CPU: 1 UID: 0 PID: 6352 Comm: syz.3.25 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 RIP: 0010:populate_free_space_tree+0x700/0x710 fs/btrfs/free-space-tree.c:1115 Code: ff ff e8 d3 (...) RSP: 0018:ffffc9000430f780 EFLAGS: 00010246 RAX: 0000000000000043 RBX: ffff88805b709630 RCX: fea61d0e2e79d000 RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000 RBP: ffffc9000430f8b0 R08: ffffc9000430f4a7 R09: 1ffff92000861e94 R10: dffffc0000000000 R11: fffff52000861e95 R12: 0000000000000001 R13: 1ffff92000861f00 R14: dffffc0000000000 R15: 0000000000000000 FS: 00007f424d9fe6c0(0000) GS:ffff888125afc000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fd78ad212c0 CR3: 0000000076d68000 CR4: 00000000003526f0 Call Trace: btrfs_rebuild_free_space_tree+0x1ba/0x6d0 fs/btrfs/free-space-tree.c:1364 btrfs_start_pre_rw_mount+0x128f/0x1bf0 fs/btrfs/disk-io.c:3062 btrfs_remount_rw fs/btrfs/super.c:1334 [inline] btrfs_reconfigure+0xaed/0x2160 fs/btrfs/super.c:1559 reconfigure_super+0x227/0x890 fs/super.c:1076 do_remount fs/namespace.c:3279 [inline] path_mount+0xd1a/0xfe0 fs/namespace.c:4027 do_mount fs/namespace.c:4048 [inline] __do_sys_mount fs/namespace.c:4236 [inline] __se_sys_mount+0x313/0x410 fs/namespace.c:4213 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f424e39066a Code: d8 64 89 02 (...) RSP: 002b:00007f424d9fde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f424d9fdef0 RCX: 00007f424e39066a RDX: 0000200000000180 RSI: 0000200000000380 RDI: 0000000000000000 RBP: 0000200000000180 R08: 00007f424d9fdef0 R09: 0000000000000020 R10: 0000000000000020 R11: 0000000000000246 R12: 0000200000000380 R13: 00007f424d9fdeb0 R14: 0000000000000000 R15: 00002000000002c0 Modules linked in: ---[ end trace 0000000000000000 ]---

CVSS v3
—
EchelonGraph score
Not yet assessedNo source has published severity data for this CVE yet — no CVSS score from NVD or a CNA, no GitHub advisory, and it is not in CISA KEV. This is not a rating of zero; we cannot assess it yet.
EG Score
—
EG Risk
—
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

October 30, 2025

Last Modified

April 15, 2026

References (5)

Patch Availability(16)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-oracle-64k-6.17 (6.17.0-1007.7) @ questing2026-05-21ubuntu
ubuntulinux-virtual-hwe-24.04-edge (6.17.0-14.14) @ questing2026-05-21ubuntu
ubuntulinux-tools-gcp-64k-6.17 (6.17.0-1007.7) @ questing2026-05-21ubuntu
ubuntulinux-tools-oem-6.17 (6.17.0-1011.11) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-6.17 (6.17.0-1008.8) @ questing2026-05-21ubuntu
ubuntulinux-virtual-6.8 (6.8.0-106.106) @ noble2026-05-21ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1045.46) @ noble2026-05-21ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1052.55+fips1) @ noble2026-05-21ubuntu
ubuntulinux-tools-aws-edge (6.8.0-1050.53~22.04.1) @ jammy2026-05-21ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1049.52.1) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1052.58+fips1) @ noble2026-05-21ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1029.30) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1051.57) @ noble2026-05-21ubuntu
ubuntulinux-tools-raspi-realtime-6.8 (6.8.0-2040.41) @ noble2026-05-21ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-05-21ubuntu
linuxKernel @ 6.1.158—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

All Vendor Advisories

(16)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 7× in last 7d / 37× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 134 total refreshes for this CVE.

  1. 2026-08-04 15:09 UTCEPSS rescore
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  1. 2026-07-15 16:57 UTCEPSS rescore
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  9. 2026-07-10 03:23 UTCOSV refresh
  10. 2026-07-09 19:09 UTCEPSS rescore
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  69. 2026-06-01 13:51 UTCEPSS rescore
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Frequently asked(4)

What is CVE-2025-40100?
CVE-2025-40100 is a publicly disclosed vulnerability published on October 30, 2025. In the Linux kernel, the following vulnerability has been resolved: btrfs: do not assert we found block group item when creating free space tree Currently, when building a free space tree at populatefreespace_tree(), if we are not using the block group tree feature, we always expect to find block…
When was CVE-2025-40100 disclosed?
CVE-2025-40100 was first published in the National Vulnerability Database on October 30, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-40100 actively exploited?
CVE-2025-40100 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 91.4% of all scored CVEs.
How do I remediate CVE-2025-40100?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-40100, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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