Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-64567— btrfs: reject free space cache with more entries than pages

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 3.2版本存在安全漏洞，该漏洞源于加载v1空闲空间缓存时未验证num_entries字段，导致越界读取，可能造成内核崩溃。

CVSS 7.8 · High EPSS 0.12% · P2

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 5b0e95bf607ddd59b39f52d3d55e6581c817b530< 8ded74c654a982dc8581a17b0caa7fcedb20de69 affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< c9c38066b6446e83668c041702bb639b0ca49363 affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< 094734c7aaa2b36751dc32480a680a4952685e78 affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< 33878ba25e2638bc0c61623d7a05c9ca2b74c039 affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< 404a0b986e0b6e79738fdf1f0ebbbc43b9acd2a2 affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< 5e1b2ca6b34939e70fb0785e8222b53cf060016f affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< f9fef131fa3f59b857217f522fa5ea430d1b707c affected
5b0e95bf607ddd59b39f52d3d55e6581c817b530< a2d8d5647ed854e38f941741aea45b9eb15a6350 affected
… +10 more rows
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-64567

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
btrfs: reject free space cache with more entries than pages
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: reject free space cache with more entries than pages When loading a v1 free space cache, __load_free_space_cache() takes num_entries and num_bitmaps straight from the on-disk btrfs_free_space_header. That header is stored in the tree_root under a key with type 0, which the tree-checker has no case for, so neither count is validated before the load trusts it. The load loops num_entries times and maps the next page whenever the current one runs out, going through io_ctl_check_crc() -> io_ctl_map_page(), which does io_ctl->pages[io_ctl->index++]. But pages[] is allocated in io_ctl_init() from the cache inode's i_size, not from num_entries: num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); io_ctl->pages = kcalloc(num_pages, sizeof(struct page *), GFP_NOFS); So if num_entries claims more records than the pages can hold, io_ctl->index runs off the end of pages[]. The write side never hits this because io_ctl_add_entry() and io_ctl_add_bitmap() both stop once io_ctl->index >= io_ctl->num_pages; the read side just never had the same check. To trigger it, take a clean cache (num_entries = <N> here), set num_entries in the header to 0x10000, and fix up the leaf checksum so it still passes the tree-checker. The cache inode has i_size = 65536, so num_pages is 16 and pages[] is a 16-pointer (kmalloc-128) array. The load now tries to read 65536 entries, io_ctl->index walks up to 16, and pages[16] is read past the array: BUG: KASAN: slab-out-of-bounds in io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565) Read of size 8 at addr ffff88800c833a80 by task kworker/u8:3/58 io_ctl_check_crc (fs/btrfs/free-space-cache.c:420 fs/btrfs/free-space-cache.c:565) __load_free_space_cache (fs/btrfs/free-space-cache.c:655 fs/btrfs/free-space-cache.c:820) load_free_space_cache (fs/btrfs/free-space-cache.c:1017) caching_thread (fs/btrfs/block-group.c:880) btrfs_work_helper (fs/btrfs/async-thread.c:312) process_one_work worker_thread kthread ret_from_fork free-space-cache.c:420 is io_ctl_map_page(), inlined into io_ctl_check_crc() at line 565, which is why that is the frame KASAN names. The out-of-bounds slot is then treated as a struct page and handed to crc32c(), so the bad read turns into a GP fault. Add the missing check to io_ctl_check_crc(), which is where both the entry loop and the bitmap loop end up. When num_entries is too large the load now fails like any corrupt cache: __load_free_space_cache() drops it and rebuilds the free space from the extent tree, so a valid cache is never rejected.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一款操作系统内核。 Linux kernel 3.2版本存在安全漏洞，该漏洞源于加载v1空闲空间缓存时未验证num_entries字段，导致越界读取，可能造成内核崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 5b0e95bf607ddd59b39f52d3d55e6581c817b530 ~ 8ded74c654a982dc8581a17b0caa7fcedb20de69 -
Linux Linux 3.2 -

II. Public POCs for CVE-2026-64567

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-64567

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-64567 (8)

Same Patch Batch · Linux · 2026-08-05 · 17 CVEs total

CVE-2026-64566 9.8 CRITICAL xfrm: iptfs: propagate SKBFL_SHARED_FRAG in iptfs_skb_add_frags()
CVE-2026-64578 8.2 HIGH ksmbd: validate compound request size before reading StructureSize2
CVE-2026-64568 7.8 HIGH wifi: mac80211: fix unsol_bcast_probe_resp double free on alloc failure
CVE-2026-64570 7.8 HIGH wifi: mac80211: fix fils_discovery double free on alloc failure
CVE-2026-64574 7.8 HIGH wifi: mac80211: tear down new links on vif update error path
CVE-2026-64575 7.8 HIGH bpf: tcp: fix double sock release on batch realloc
CVE-2026-64580 7.8 HIGH xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst()
CVE-2026-64581 7.8 HIGH xfrm: fix sk_dst_cache double-free in xfrm_user_policy()
CVE-2026-64582 7.8 HIGH RDMA/rxe: Fix a use-after-free problem in rxe_mmap
CVE-2026-64577 7.5 HIGH gtp: check skb_pull_data() return in gtp1u_send_echo_resp()
CVE-2026-64576 7.1 HIGH nexthop: initialize extack in nh_res_bucket_migrate()
CVE-2026-64569 mpls: fix NULL deref in mpls_valid_fib_dump_req() on CONFIG_INET=n
CVE-2026-64571 wifi: p54: validate RX frame length in p54_rx_eeprom_readback()
CVE-2026-64572 ipv4: fib: free fib_alias with kfree_rcu() on insert error path
CVE-2026-64573 Bluetooth: qca: fix NVM tag length underflow in TLV parser
CVE-2026-64579 xfrm: policy: preallocate inexact bins before xfrm_hash_rebuild reinsert

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-64567

No comments yet

Leave a comment