Answer in brief
CVE-2025-37856 records a Unknown severity vulnerability in btrfs: harden block_group::bg_list against list_del() races. 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.
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.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <909e60fb469d4101c6b08cf6e622efb062bb24a1 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <185fd73e5ac06027c4be9a129e59193f6a3ef202 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <7511e29cf1355b2c47d0effb39e463119913e2f6 || edf3b5aadb2515c808200b904baa5b70a727f0ac || 01eca70ef8cf499d0cb6d1bbd691558e7792cf17 || 5d19abcffd8404078dfa7d7118cec357b5e7bc58 || >=5.15.128 <5.16 || >=6.1.47 <6.2 || >=6.4.12 <6.5 | bf089c4d1141b27332c092b1dcca5022c415a3b6, 909e60fb469d4101c6b08cf6e622efb062bb24a1, 185fd73e5ac06027c4be9a129e59193f6a3ef202, 7511e29cf1355b2c47d0effb39e463119913e2f6, 5.16, 6.2, 6.5 |
| Linux/Linuxgeneric | 6.5 | Not reported |
Published upstream
May 9, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.
Quoted source text, attributed separately from HOL analysis.
Answer in brief
CVE-2025-37856 records a Unknown severity vulnerability in btrfs: harden block_group::bg_list against list_del() races. 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.
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.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <909e60fb469d4101c6b08cf6e622efb062bb24a1 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <185fd73e5ac06027c4be9a129e59193f6a3ef202 || >=a9f189716cf15913c453299d72f69c51a9b0f86b <7511e29cf1355b2c47d0effb39e463119913e2f6 || edf3b5aadb2515c808200b904baa5b70a727f0ac || 01eca70ef8cf499d0cb6d1bbd691558e7792cf17 || 5d19abcffd8404078dfa7d7118cec357b5e7bc58 || >=5.15.128 <5.16 || >=6.1.47 <6.2 || >=6.4.12 <6.5 | bf089c4d1141b27332c092b1dcca5022c415a3b6, 909e60fb469d4101c6b08cf6e622efb062bb24a1, 185fd73e5ac06027c4be9a129e59193f6a3ef202, 7511e29cf1355b2c47d0effb39e463119913e2f6, 5.16, 6.2, 6.5 |
| Linux/Linuxgeneric | 6.5 | Not reported |
Published upstream
May 9, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.
Quoted source text, attributed separately from HOL analysis.