Linux Kernel up to 7.2.5 btrfs btrfs_delayed_refs_rsv_refill denial of service

Summaryinfo

A vulnerability labeled as critical has been found in Linux Kernel up to 7.2.5. This affects the function btrfs_delayed_refs_rsv_refill of the component btrfs. Such manipulation leads to denial of service. This vulnerability is documented as CVE-2026-90266. The attack can be executed remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Linux Kernel up to 7.2.5. Affected by this issue is the function btrfs_delayed_refs_rsv_refill of the component btrfs. The manipulation with an unknown input leads to a denial of service vulnerability. Using CWE to declare the problem leads to CWE-404. The product does not release or incorrectly releases a resource before it is made available for re-use. Impacted is availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: btrfs: zoned: don't force read-only on transient -EAGAIN from reloc merge On a zoned FS, btrfs_delayed_refs_rsv_refill() returns -EAGAIN whenever the over-committed metadata plus the zone_unusable bytes exceeds the usable size in a metadata block-group to avoid heavy over-commit of metadata and early ENOSPC in one transaction. If this happens while doing reclaim, the transaction is getting aborted. Treat -EAGAIN as a soft, retryable condition in case of block-group reclaim.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-90266 since 09/11/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 09/17/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch 8249dfe46337d599e2087b77282b/e549093c11a2fff8430df3dfbdb45eb9811a69a5 is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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