CVE-2026-89704

CVE CVE-2026-89704EUVD EUVD-2026-76616Published 2026-09-11T19:46:21.000ZLast changed 2026-09-14T12:02:06.000ZCVSS 7.5

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: nfsd: sample writeback error cursor before async COPY loop _nfsd_copy_file_range() samples dst->f_wb_err into "since" after the copy loop, then uses it to detect writeback errors via filemap_check_wb_err() once vfs_fsync_range() returns. Because the nfsd_file cache reuses a single struct file across requests targeting the same inode, a concurrent COMMIT or stable WRITE on dst advances dst->f_wb_err to the current mapping->wb_err via file_check_and_advance_wb_err() during its own vfs_fsync_range(). If that advancement lands between the writeback error appearing in mapping->wb_err and the COPY worker sampling "since", the worker captures the already-advanced cursor, errseq_check() sees cur == since and returns zero, and NFSD4_COPY_F_COMMITTED is set even though writeback failed. CB_OFFLOAD then encodes wr_stable_how = FILE_SYNC4, the client treats the copied data as durable, and the failure becomes silent data loss. Sample since once at the start of the function. The cursor then reflects state in effect before this COPY issues any writes, and filemap_check_wb_err() detects any error that occurs during the copy regardless of which thread first observes it. This matches the pattern used by nfsd_vfs_write() and nfsd4_clone_file_range().

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux patch: 6.1.188; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <52b2db7a72e19ac2686fa4b2a52406661e7bf9e2; patch: 5.10.270; patch: 6.18.50; 5.17; patch: 6.12.109; 5.15.49 <5.15.221; patch: 5.15.221; 5.10.124 <5.10.270; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <4728504c021656128a07f4693af80ed4a5fcc863; 3145fe0ebb16e1715ad541a301bc6675c8375fcd <9f539a1c0791f907eb4e6d04b43178d9962e2def; patch: 0; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <322422d66d1a04434a0dcc0c9d3a4c4b3f225117; patch: 6.6.157; patch: 7.2.4; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <8277d4a11ae2cb5495842be558fd946032c24363; f14816f2f928c560d28ba344af689f56efcd6f55 <435e4246c7dfff2fbd76dfdbf91975d5d9f788c9; patch: 7.3-rc1; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <20a67a7d18221af736f124770c2c5e859b479046; 555dbf1a9aac6d3150c8b52fa35f768a692f4eeb <a1cbafe756cd5e6ab0e099062f37da7a5b081169

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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