Linux: Out-of-bounds Write
CVE-2026-31452 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions 110d7ef602659ce4d7947c5480f7ca2779696aaf, f53a5d9f32924bc2a810d2df243b7714da58b636, c047332be7195833a5c5126816c2502df8269fe4 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 110d7ef602659ce4d7947c5480f7ca2779696aaf or f53a5d9f32924bc2a810d2df243b7714da58b636 or c047332be7195833a5c5126816c2502df8269fe4 or 699bac4d4c951974d55b045c983d1de777215949, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.168 or 6.6.131, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, 110d7ef602659ce4d7947c5480f7ca2779696aaf; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, f53a5d9f32924bc2a810d2df243b7714da58b636; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, c047332be7195833a5c5126816c2502df8269fe4; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, 699bac4d4c951974d55b045c983d1de777215949; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, 7920dcc571cef3d8aa9ee109c136125d61d41669; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, 93cb2d103e5c707de0f7ad58a39b7f0fddc27aa6; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, 07c1a31af18290054da3d18221b8bf58983c5d3a; 67cf5b09a46f72e048501b84996f2f77bc42e947 up to, but not including, ed9356a30e59c7cc3198e7fc46cfedf3767b9b17; and 1 more ranges | 110d7ef602659ce4d7947c5480f7ca2779696aaf, f53a5d9f32924bc2a810d2df243b7714da58b636, c047332be7195833a5c5126816c2502df8269fe4, 699bac4d4c951974d55b045c983d1de777215949, 7920dcc571cef3d8aa9ee109c136125d61d41669, 93cb2d103e5c707de0f7ad58a39b7f0fddc27aa6 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 3.8 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.168; 6.2 up to, but not including, 6.6.131; 6.7 up to, but not including, 6.12.80; 6.13 up to, but not including, 6.18.21; 6.19 up to, but not including, 6.19.11; 7.0 | 5.10.253, 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21 |
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
- LowA basic user account is enough.
- 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:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: ext4: convert inline data to extents when truncate exceeds inline size Add a check in ext4_setattr() to convert files from inline data storage to extent-based storage when truncate() grows the file size beyond the inline capacity. This prevents the filesystem from entering an inconsistent state where the inline data flag is set but the file size exceeds what can be stored inline. Without this fix, the following sequence causes a kernel BUG_ON(): 1. Mount filesystem with inode that has inline flag set and small size 2. truncate(file, 50MB) - grows size but inline flag remains set 3. sendfile() attempts to write data 4. ext4_write_inline_data() hits BUG_ON(write_size > inline_capacity) The crash occurs because ext4_write_inline_data() expects inline storage to accommodate the write, but the actual inline capacity (~60 bytes for i_block + ~96 bytes for xattrs) is far smaller than the file size and write request. The fix checks if the new size from setattr exceeds the inode's actual inline capacity (EXT4_I(inode)->i_inline_size) and converts the file to extent-based storage before proceeding with the size change. This addresses the root cause by ensuring the inline data flag and file size remain consistent during truncate operations.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/07c1a31af18290054da3d18221b8bf58983c5d3a
- git.kernel.org/stable/c/110d7ef602659ce4d7947c5480f7ca2779696aaf
- git.kernel.org/stable/c/699bac4d4c951974d55b045c983d1de777215949
- git.kernel.org/stable/c/7920dcc571cef3d8aa9ee109c136125d61d41669
- git.kernel.org/stable/c/93cb2d103e5c707de0f7ad58a39b7f0fddc27aa6
- git.kernel.org/stable/c/c047332be7195833a5c5126816c2502df8269fe4
- git.kernel.org/stable/c/ed9356a30e59c7cc3198e7fc46cfedf3767b9b17
- git.kernel.org/stable/c/f53a5d9f32924bc2a810d2df243b7714da58b636
Other references
Recent Out-of-bounds Write vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.1 High severity
- 8.8 High severity
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