CVE-2026-90260: Linux kernel · btrfs: zoned: don't clobber the extent buffer when zeroing it out
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in efa5084d08030aa557fdefa3e4a73b2501b7d207 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in efa5084d08030aa557fdefa3e4a73b2501b7d207, db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c, 92484ad014f2e2b0e0e7bbc1610951e978cf557c +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 17 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade Linux kernel to efa5084d08030aa557fdefa3e4a73b2501b7d207, db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c, 92484ad014f2e2b0e0e7bbc1610951e978cf557c or 98e3747587f9f87f010d8d7e55786216249a94af.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: don't clobber the extent buffer when zeroing it out On a zoned filesystem a freed-but-still-dirty tree block is written out as zeros (EXTENT_BUFFER_ZONED_ZEROOUT) only to keep the zone write pointer advancing. btree_csum_one_bio() implemented this by memzeroing the extent buffer's own folios before submission. That destroys the in-memory buffer while it may still be referenced. In particular btrfs_free_tree_block() can run on it afterwards and reads the header to add a delayed reference; once the header has been zeroed it frees bytenr 0 and corrupts the extent tree (the btrfs_header_bytenr(buf) != 0 ASSERT in btrfs_free_tree_block(), or an "unable to find ref" abort). It is flaky and reproduces under fsstress, e.g. generic/461 and generic/013. Write the zeros to disk from the shared zero page instead and leave the extent buffer content untouched, so any later reference - including the delayed reference from btrfs_free_tree_block() - still sees a valid header. end_bbio_meta_write() now clears writeback on the buffer's own folios, as the bio no longer carries them.
References
- git.kernel.org/stable/c/efa5084d08030aa557fdefa3e4a73b2501b7d207 (opens in a new tab)
- git.kernel.org/stable/c/92484ad014f2e2b0e0e7bbc1610951e978cf557c (opens in a new tab)
- git.kernel.org/stable/c/98e3747587f9f87f010d8d7e55786216249a94af (opens in a new tab)
- git.kernel.org/stable/c/db4b9eefc8ee0bcaeee4d5e6a7313905f6a2fe7c (opens in a new tab)