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CVE-2026-53393— nfsd: reset write verifier on deferred writeback errors

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存在安全漏洞，该漏洞源于nfsd在处理延迟回写错误时未重置写入验证器，可能导致客户端的数据丢失。

AI Predicted 5.9 Difficulty: Moderate EPSS 0.13% · P3

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 20

VendorProduct Version RangeStatus
Linux Linux f14816f2f928c560d28ba344af689f56efcd6f55< b8e5894e56cff70fa245628fe16f0ad6367f8090 affected
3145fe0ebb16e1715ad541a301bc6675c8375fcd< bc2baca02ec56da7707a74ed5d340b0a1dff1841 affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< 43b65d2997963e80e8d8d86520bcb1e0751227de affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< 666e837b247fcadf2d8d508b9b0e49d720393eb4 affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< 1dd664b39774a9c89b72de8e59bf9ef4b3aaff2e affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< 4367afc119c51e17a616f6908772b7e2c2c4013f affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< b027cca33c97354149fcc0ddeede4525c41093cd affected
555dbf1a9aac6d3150c8b52fa35f768a692f4eeb< 2090b05803faab8a9fa62fbff871007862cac1b7 affected
… +12 more rows
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I. Basic Information for CVE-2026-53393

Vulnerability Information
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Vulnerability Title
nfsd: reset write verifier on deferred writeback errors
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: nfsd: reset write verifier on deferred writeback errors nfsd_vfs_write() and nfsd_commit() both call filemap_check_wb_err() to detect deferred writeback errors, but neither rotates the server's write verifier (nn->writeverf) when this check fails. Every other durable-storage-failure path in these functions calls commit_reset_write_verifier() before returning an error. The missing rotation means clients holding UNSTABLE write data under the current verifier will COMMIT, receive the unchanged verifier back, and conclude their data is durable — silently dropping data that failed writeback. This violates the UNSTABLE+COMMIT durability contract (RFC 1813 §3.3.7, RFC 8881 §18.32). Add commit_reset_write_verifier() calls at both filemap_check_wb_err() error sites, matching the pattern used by adjacent error paths in the same functions. The helper already filters -EAGAIN and -ESTALE internally, so the calls are unconditionally safe.
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存在安全漏洞，该漏洞源于nfsd在处理延迟回写错误时未重置写入验证器，可能导致客户端的数据丢失。
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 f14816f2f928c560d28ba344af689f56efcd6f55 ~ b8e5894e56cff70fa245628fe16f0ad6367f8090 -
Linux Linux 5.17 -

II. Public POCs for CVE-2026-53393

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III. Intelligence Information for CVE-2026-53393

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Patches & Fixes for CVE-2026-53393 (8)

Same Patch Batch · Linux · 2026-07-19 · 429 CVEs total

CVE-2026-63795 10.0 CRITICAL 9p: avoid putting oldfid in p9_client_walk() error path
CVE-2026-64046 9.8 CRITICAL net: tls: prevent chain-after-chain in plain text SG
CVE-2026-63984 9.8 CRITICAL ipv6: rpl: fix hdrlen overflow in ipv6_rpl_srh_decompress()
CVE-2026-63800 9.8 CRITICAL pNFS: Fix use-after-free in pnfs_update_layout()
CVE-2026-63979 9.8 CRITICAL net/handshake: hand off the pinned file reference to accept_doit
CVE-2026-64142 9.8 CRITICAL ksmbd: close durable scavenger races against m_fp_list lookups
CVE-2026-63978 9.8 CRITICAL net/handshake: Drain pending requests at net namespace exit
CVE-2026-64056 9.8 CRITICAL net: ethernet: cortina: Make RX SKB per-port
CVE-2026-63808 9.8 CRITICAL exfat: fix potential use-after-free in exfat_find_dir_entry()
CVE-2026-64055 9.8 CRITICAL net: ethernet: cortina: Carry over frag counter
CVE-2026-63922 9.8 CRITICAL ipv6: exthdrs: refresh nh after handling HAO option
CVE-2026-64033 9.8 CRITICAL RDMA/rtrs: Fix use-after-free in path file creation cleanup
CVE-2026-64113 9.8 CRITICAL ixgbevf: fix use-after-free in VEPA multicast source pruning
CVE-2026-63825 9.8 CRITICAL gcov: use atomic counter updates to fix concurrent access crashes
CVE-2026-64016 9.8 CRITICAL ksmbd: fix durable reconnect error path file lifetime
CVE-2026-64122 9.8 CRITICAL net/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
CVE-2026-64047 9.8 CRITICAL net: tls: fix off-by-one in sg_chain entry count for wrapped sk_msg ring
CVE-2026-64035 9.8 CRITICAL igc: set tx buffer type for SMD frames
CVE-2026-64025 9.8 CRITICAL bpf, skmsg: fix verdict sk_data_ready racing with ktls rx
CVE-2026-64150 9.8 CRITICAL netfilter: nft_inner: release local_lock before re-enabling softirqs

Showing top 20 of 429 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-53393

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