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CVE-2026-31437— netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry

EPSS 0.02% · P6
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I. Basic Information for CVE-2026-31437

Vulnerability Information
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Vulnerability Title
netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry When a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path in netfs_unbuffered_write() unconditionally calls stream->prepare_write() without checking if it is NULL. Filesystems such as 9P do not set the prepare_write operation, so stream->prepare_write remains NULL. When get_user_pages() fails with -EFAULT and the subrequest is flagged for retry, this results in a NULL pointer dereference at fs/netfs/direct_write.c:189. Fix this by mirroring the pattern already used in write_retry.c: if stream->prepare_write is NULL, skip renegotiation and directly reissue the subrequest via netfs_reissue_write(), which handles iterator reset, IN_PROGRESS flag, stats update and reissue internally.
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于netfs在netfs_unbuffered_write()重试路径中存在空指针取消引用，可能导致stream->prepare_write为NULL时调用失败。
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

VendorProductAffected VersionsCPESubscribe
LinuxLinux 72d08d2839649d1c5efbe375751f4473fa4486af ~ a4d1b4ba9754bac3efebd06f583a44a7af52c0ab -
LinuxLinux 6.18.17 ~ 6.18.21 -

II. Public POCs for CVE-2026-31437

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III. Intelligence Information for CVE-2026-31437

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Same Patch Batch · Linux · 2026-04-22 · 100 CVEs total

CVE-2026-314639.8 CRITICALiomap: fix invalid folio access when i_blkbits differs from I/O granularity
CVE-2026-314369.8 CRITICALdmaengine: idxd: fix possible wrong descriptor completion in llist_abort_desc()
CVE-2026-314449.8 CRITICALksmbd: fix use-after-free and NULL deref in smb_grant_oplock()
CVE-2026-314789.8 CRITICALksmbd: replace hardcoded hdr2_len with offsetof() in smb2_calc_max_out_buf_len()
CVE-2026-315019.8 CRITICALnet: ti: icssg-prueth: fix use-after-free of CPPI descriptor in RX path
CVE-2026-314489.4 CRITICALext4: avoid infinite loops caused by residual data
CVE-2026-314328.8 HIGHksmbd: fix OOB write in QUERY_INFO for compound requests
CVE-2026-314338.8 HIGHksmbd: fix potencial OOB in get_file_all_info() for compound requests
CVE-2026-314358.8 HIGHnetfs: Fix read abandonment during retry
CVE-2026-314508.8 HIGHext4: publish jinode after initialization
CVE-2026-314768.2 HIGHksmbd: do not expire session on binding failure
CVE-2026-314648.1 HIGHscsi: ibmvfc: Fix OOB access in ibmvfc_discover_targets_done()
CVE-2026-315138.1 HIGHBluetooth: L2CAP: Fix stack-out-of-bounds read in l2cap_ecred_conn_req
CVE-2026-314907.8 HIGHdrm/xe/pf: Fix use-after-free in migration restore
CVE-2026-314537.8 HIGHxfs: avoid dereferencing log items after push callbacks
CVE-2026-314947.8 HIGHnet: macb: use the current queue number for stats
CVE-2026-315027.8 HIGHteam: fix header_ops type confusion with non-Ethernet ports
CVE-2026-314497.8 HIGHext4: validate p_idx bounds in ext4_ext_correct_indexes
CVE-2026-315047.8 HIGHnet: fix fanout UAF in packet_release() via NETDEV_UP race
CVE-2026-315057.8 HIGHiavf: fix out-of-bounds writes in iavf_get_ethtool_stats()

Showing top 20 of 100 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-31437

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