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CVE-2026-64419— mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()

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 6.0版本存在安全漏洞，该漏洞源于在shrinker_debugfs_count_show()函数中，在RCU读锁定期间调用了可能睡眠的css_rstat_flush函数，可能导致内核崩溃或拒绝服务。

AI Predicted 3.3 Difficulty: Easy EPSS 0.12% · P2

Possible ATT&CK Techniques 1 AI

T1041 · Exfiltration Over C2 Channel

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux 5035ebc644aec92d55d1bbfe042f35341e4bffb5< de5f69b8dae8698ac5e48dfcd30017887cdf4e5a affected
5035ebc644aec92d55d1bbfe042f35341e4bffb5< e441cbfbd0eaa6404278e985033c33caba4db767 affected
5035ebc644aec92d55d1bbfe042f35341e4bffb5< 2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 affected
5035ebc644aec92d55d1bbfe042f35341e4bffb5< 560e21e8ccff813e84d05f6500907c549a3d6985 affected
5035ebc644aec92d55d1bbfe042f35341e4bffb5< 86237e56091e70f09c0fbf217f9d9c0e08f556c4 affected
5035ebc644aec92d55d1bbfe042f35341e4bffb5< b902890c62d200b3509cb5e09cf1e0a66553c128 affected
6.0 affected
< 6.0 unaffected
… +6 more rows
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I. Basic Information for CVE-2026-64419

Vulnerability Information
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Vulnerability Title
mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() Reading the debugfs "count" file of a memcg-aware shrinker can sleep inside an RCU read-side critical section: BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421 RCU nest depth: 1, expected: 0 css_rstat_flush mem_cgroup_flush_stats zswap_shrinker_count shrinker_debugfs_count_show shrinker_debugfs_count_show() invokes the ->count_objects() callback under rcu_read_lock(). The zswap callback flushes memcg stats via css_rstat_flush(), which may sleep, so it must not run under RCU. The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally and returns a memcg holding a css reference (dropped on the next iteration or by mem_cgroup_iter_break()), so the memcg stays alive without it. The shrinker is kept alive by the open debugfs file: shrinker_free() removes the debugfs entries via debugfs_remove_recursive(), which waits for in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). The sibling "scan" handler already invokes the sleeping ->scan_objects() callback with no RCU section. Drop the rcu_read_lock()/rcu_read_unlock().
Source: CVE Program / CVE List V5
CVSS Information
N/A
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 6.0版本存在安全漏洞，该漏洞源于在shrinker_debugfs_count_show()函数中，在RCU读锁定期间调用了可能睡眠的css_rstat_flush函数，可能导致内核崩溃或拒绝服务。
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 5035ebc644aec92d55d1bbfe042f35341e4bffb5 ~ de5f69b8dae8698ac5e48dfcd30017887cdf4e5a -
Linux Linux 6.0 -

II. Public POCs for CVE-2026-64419

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III. Intelligence Information for CVE-2026-64419

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Patches & Fixes for CVE-2026-64419 (6)

Same Patch Batch · Linux · 2026-07-25 · 274 CVEs total

CVE-2026-64355 9.8 CRITICAL bpf: Reject fragmented frames in devmap
CVE-2026-64459 9.8 CRITICAL tcp: restore RCU grace period in tcp_ao_destroy_sock
CVE-2026-64303 9.8 CRITICAL spi: fsl-lpspi: terminate the RX channel on TX prepare failure path
CVE-2026-64439 9.8 CRITICAL crypto: krb5 - filter out async aead implementations at alloc
CVE-2026-64410 9.8 CRITICAL netfilter: flowtable: IPIP tunnel hardware offload is not yet support
CVE-2026-64399 9.8 CRITICAL ksmbd: add permission checks for FSCTL_DUPLICATE_EXTENTS_TO_FILE
CVE-2026-64397 9.8 CRITICAL ksmbd: serialize QUERY_DIRECTORY requests per file
CVE-2026-64391 9.8 CRITICAL ksmbd: use opener credentials for ADS I/O
CVE-2026-64387 9.8 CRITICAL smb: client: fix query directory replay double-free
CVE-2026-64386 9.8 CRITICAL smb: client: fix query_info() replay double-free
CVE-2026-64385 9.8 CRITICAL smb: client: fix double-free in SMB2_ioctl() replay
CVE-2026-64383 9.8 CRITICAL smb: client: fix double-free in SMB2_flush() replay
CVE-2026-64384 9.8 CRITICAL smb: client: fix change notify replay double-free
CVE-2026-64268 9.8 CRITICAL RDMA/siw: bound Read Response placement to the RREAD length
CVE-2026-64523 9.8 CRITICAL net/handshake: Take a long-lived file reference at submit
CVE-2026-64269 9.1 CRITICAL RDMA/rtrs-srv: Bound RDMA-Write length to chunk size in rdma_write_sg
CVE-2026-64257 9.1 CRITICAL smb: client: reject overlapping data areas in SMB2 responses
CVE-2026-64319 9.1 CRITICAL nvmet-auth: validate reply message payload bounds against transfer length
CVE-2026-64320 9.1 CRITICAL nvmet: fix pre-auth out-of-bounds heap read in Discovery Get Log Page
CVE-2026-64393 9.1 CRITICAL ksmbd: run set info with opener credentials

Showing top 20 of 274 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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