CyberSecBulletin
CVE-2026-52915NVD status: Modified

Linux: Improper Validation of Array Index

Published Updated By the CyberSecBulletin desk

CVE-2026-52915 is a high-severity improper validation of array index vulnerability in Linux, with a CVSS 3.1 base score of 7.1 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 2d523ba48d4ecc46acfb6aba548292cfcce1ac02, 588933f1a2ca5ff99274f8c9f25dc3a25d0191c3, 784aadea7a108c9f90985683caa87fb0198c6a39 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 0.13% 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 2d523ba48d4ecc46acfb6aba548292cfcce1ac02 or 588933f1a2ca5ff99274f8c9f25dc3a25d0191c3 or 784aadea7a108c9f90985683caa87fb0198c6a39 or 41ec2e242f1702e8370ddfe14d22b7a766021c3e, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.142, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 2d523ba48d4ecc46acfb6aba548292cfcce1ac02; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 588933f1a2ca5ff99274f8c9f25dc3a25d0191c3; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 784aadea7a108c9f90985683caa87fb0198c6a39; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 41ec2e242f1702e8370ddfe14d22b7a766021c3e; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, db0250470f023f159094052c0bd5ab026a88ae93; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 57b0ac5e1b46f1f0338dff392ef2092e2871b412; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 6feb43c0995ab3a9c826707eb46541a1696fe4f7; 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 up to, but not including, 4322dcde6b4173c2d8e8e6118ed290794263bcc8; and 1 more ranges2d523ba48d4ecc46acfb6aba548292cfcce1ac02, 588933f1a2ca5ff99274f8c9f25dc3a25d0191c3, 784aadea7a108c9f90985683caa87fb0198c6a39, 41ec2e242f1702e8370ddfe14d22b7a766021c3e, db0250470f023f159094052c0bd5ab026a88ae93, 57b0ac5e1b46f1f0338dff392ef2092e2871b412
LinuxLinux Kernel2.6.12.1 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.142; 6.7 up to, but not including, 6.12.92; 6.13 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; 2.6.12; and 1 more ranges5.10.258, 5.15.209, 6.1.175, 6.6.142, 6.12.92, 6.18.34

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
NoneNothing can be modified.
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:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ip6t_hbh: reject oversized option lists struct ip6t_opts stores at most IP6T_OPTS_OPTSNR option descriptors, but hbh_mt6_check() does not reject larger optsnr values supplied from userspace. Validate optsnr in the rule setup path so only match data that fits the fixed-size opts array can be installed. This follows the existing xtables pattern of rejecting invalid user-provided counts in checkentry() and keeps the packet matching path unchanged. `struct ip6t_opts` has a fixed `opts[IP6T_OPTS_OPTSNR]` array, where `IP6T_OPTS_OPTSNR` is 16, then off-by-one array access is possible: [ 137.924693][ T8692] UBSAN: array-index-out-of-bounds in ../net/ipv6/netfilter/ip6t_hbh.c:110:29 [ 137.926167][ T8692] index 16 is out of range for type '__u16 [16]'

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Validation of Array Index

The product uses untrusted input when calculating or using an array index, but the product does not validate or incorrectly validates the index to ensure the index references a valid position within the array.

How developers prevent this class of flaw

  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, Ada allows the programmer to constrain the values of a variable and languages such as Java and Ruby will allow the programmer to handle exceptions when an out-of-bounds index is accessed.
  • Use a CPU and operating system that offers Data Execution Protection (using hardware NX or XD bits) or the equivalent techniques that simulate this feature in software, such as PaX. These techniques ensure that any instruction executed is exclusively at a memory address that is part of the code segment. For more information on these techniques see D3-PSEP (Process Segment Execution Prevention) from D3FEND.

More Improper Validation of Array Index vulnerabilities (CWE-129)

Timeline

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

References

Recent Improper Validation of Array Index vulnerabilities

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