Linux: Out-of-bounds Read
CVE-2026-63818 is a high-severity out-of-bounds read vulnerability in Linux, with a CVSS 3.1 base score of 8.4 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, without any action from a user. The record lists versions 210c210c92d78fdf5051bc55c5c69044b1a2150a, ad101d15716f5a24d1fa82a849f80430c805a3dd, d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 210c210c92d78fdf5051bc55c5c69044b1a2150a or ad101d15716f5a24d1fa82a849f80430c805a3dd or d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70 or d2f236196d542ccd8505736e41c3a1d3f0305f6f, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, 210c210c92d78fdf5051bc55c5c69044b1a2150a; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, ad101d15716f5a24d1fa82a849f80430c805a3dd; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, d2f236196d542ccd8505736e41c3a1d3f0305f6f; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, 550511a2470f6d204fa07b331f048bd2d3c51280; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, 8aad54746c251f2c2370118df766c0c82e2d2091; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, 2e12381d4495dc8b0ff042c6856022b2e359835c; 127e670abfa7fa150f6550d620ded930f5bdb4e7 up to, but not including, 846c499a65816d13f1186e3090e825e8bb8bcb8b; and 1 more ranges | 210c210c92d78fdf5051bc55c5c69044b1a2150a, ad101d15716f5a24d1fa82a849f80430c805a3dd, d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70, d2f236196d542ccd8505736e41c3a1d3f0305f6f, 550511a2470f6d204fa07b331f048bd2d3c51280, 8aad54746c251f2c2370118df766c0c82e2d2091 |
| Linux | Linux Kernel | 3.8 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.38; 6.19 up to, but not including, 7.1.3 | 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.38 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate orphan inode entry count f2fs_recover_orphan_inodes() trusts the orphan block entry_count when replaying orphan inodes from the checkpoint pack. A corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the ino[] array and interpret footer or following data as inode numbers. On a crafted image, mounting an unpatched kernel can drive orphan recovery into f2fs_bug_on() and panic the kernel. Validate entry_count before consuming entries so corrupted checkpoint data fails the mount with -EFSCORRUPTED and requests fsck instead. Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be recorded in the superblock s_errors[] field. This gives fsck a persistent hint even though mount-time orphan recovery failure may leave no chance to persist SBI_NEED_FSCK through a checkpoint.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/210c210c92d78fdf5051bc55c5c69044b1a2150a
- git.kernel.org/stable/c/2e12381d4495dc8b0ff042c6856022b2e359835c
- git.kernel.org/stable/c/550511a2470f6d204fa07b331f048bd2d3c51280
- git.kernel.org/stable/c/846c499a65816d13f1186e3090e825e8bb8bcb8b
- git.kernel.org/stable/c/8aad54746c251f2c2370118df766c0c82e2d2091
- git.kernel.org/stable/c/ad101d15716f5a24d1fa82a849f80430c805a3dd
- git.kernel.org/stable/c/d18c81f5d0ecd5796aa47d66d98f2dd54d8d0f70
- git.kernel.org/stable/c/d2f236196d542ccd8505736e41c3a1d3f0305f6f
Recent Out-of-bounds Read vulnerabilities
- 7.1 High severity
- 7.8 High severity
- 7.3 High severity
- 7.1 High severity
- 7.8 High severity
- 9.8 Critical severity
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