CyberSecBulletin
CVE-2026-64322NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-64322 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 eeb0f3e193f8e523d03e4c9e084f6b4875f50e8e, 0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9, 2d726135099313958f8975532a2e15322ff150ce 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 0.17% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to eeb0f3e193f8e523d03e4c9e084f6b4875f50e8e or 0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9 or 2d726135099313958f8975532a2e15322ff150ce or 7285276aa50d2839afb5957ffd491ad282dc8f72, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 2.6.33 or 2.6.35 or 3.1 or 3.3, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, eeb0f3e193f8e523d03e4c9e084f6b4875f50e8e; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 2d726135099313958f8975532a2e15322ff150ce; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 7285276aa50d2839afb5957ffd491ad282dc8f72; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 2a219acb2ce674d99bbd1b7b35ed8c384dac7200; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 04f4599a9efb90992d072a814960edf0cd62805d; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 7f7774b9da0ef17b87bfa238cf966ad0b3376150; 1df2ae31c724e57be9d7ac00d78db8a5dabdd050 up to, but not including, 3ec997bd5508e9b25210b5bbec89031629cdb093; and 11 more rangeseeb0f3e193f8e523d03e4c9e084f6b4875f50e8e, 0a9b79a951cfd70a9d31ca01ae2d08a20bb730e9, 2d726135099313958f8975532a2e15322ff150ce, 7285276aa50d2839afb5957ffd491ad282dc8f72, 2a219acb2ce674d99bbd1b7b35ed8c384dac7200, 04f4599a9efb90992d072a814960edf0cd62805d
LinuxLinux Kernel2.6.32.60 up to, but not including, 2.6.33; 2.6.34.14 up to, but not including, 2.6.35; 3.0.37 up to, but not including, 3.1; 3.2.23 up to, but not including, 3.3; 3.4.5 up to, but not including, 3.5; 3.5.1 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; and 5 more ranges2.6.33, 2.6.35, 3.1, 3.3, 3.5, 5.10.261

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: udf: validate sparing table length as an entry count, not a byte count udf_load_sparable_map() accepts a sparing table when sizeof(*st) + le16_to_cpu(st->reallocationTableLen) > sb->s_blocksize is false, i.e. it treats reallocationTableLen as a number of BYTES that must fit in the block. But the table is walked as an array of 8-byte sparingEntry elements: for (i = 0; i < le16_to_cpu(st->reallocationTableLen); i++) { struct sparingEntry *entry = &st->mapEntry[i]; ... entry->origLocation ... } in udf_get_pblock_spar15() and udf_relocate_blocks(). A reallocationTableLen of N therefore passes the check whenever sizeof(*st) + N <= blocksize, yet the consumers index sizeof(*st) + N * sizeof(struct sparingEntry) bytes -- up to ~8x the block. On a crafted UDF image this is an out-of-bounds read in udf_get_pblock_spar15(); udf_relocate_blocks() additionally feeds the same length to udf_update_tag(), whose crc_itu_t() reads far past the block, and its memmove() through st->mapEntry[] is an out-of-bounds write. Validate reallocationTableLen as the entry count it is, with struct_size().

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.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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