CyberSecBulletin
CVE-2026-43258NVD status: Modified

Linux: Out-of-bounds Write

Published Updated By the CyberSecBulletin desk

CVE-2026-43258 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 01cddfc34bf2a813a2773f1d607305515be55409, 5593c9b255ae73f57a8b5e696a660032acbd67da, d4ca6ca2c6f5a1d19d9014c5b36d96637846b5d6 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 0.18% 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 01cddfc34bf2a813a2773f1d607305515be55409 or 5593c9b255ae73f57a8b5e696a660032acbd67da or d4ca6ca2c6f5a1d19d9014c5b36d96637846b5d6 or 03e42b5f7ad4c2c3db8bd384bab7990d5d53c90f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.12.75 or 6.18.16 or 6.19.6, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxa48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, 01cddfc34bf2a813a2773f1d607305515be55409; a48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, 5593c9b255ae73f57a8b5e696a660032acbd67da; a48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, d4ca6ca2c6f5a1d19d9014c5b36d96637846b5d6; a48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, 03e42b5f7ad4c2c3db8bd384bab7990d5d53c90f; a48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, bab8d762a8dbb816b10011e13b87d1bca91e5f77; a48d07afdf18212de22b959715b16793c5a6e57a up to, but not including, dd5712f3379cfe760267cdd28ff957d9ab4e51c7; 2.6.1601cddfc34bf2a813a2773f1d607305515be55409, 5593c9b255ae73f57a8b5e696a660032acbd67da, d4ca6ca2c6f5a1d19d9014c5b36d96637846b5d6, 03e42b5f7ad4c2c3db8bd384bab7990d5d53c90f, bab8d762a8dbb816b10011e13b87d1bca91e5f77, dd5712f3379cfe760267cdd28ff957d9ab4e51c7
LinuxLinux Kernel2.6.16.1 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6; 2.6.166.12.75, 6.18.16, 6.19.6

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: alpha: fix user-space corruption during memory compaction Alpha systems can suffer sporadic user-space crashes and heap corruption when memory compaction is enabled. Symptoms include SIGSEGV, glibc allocator failures (e.g. "unaligned tcache chunk"), and compiler internal errors. The failures disappear when compaction is disabled or when using global TLB invalidation. The root cause is insufficient TLB shootdown during page migration. Alpha relies on ASN-based MM context rollover for instruction cache coherency, but this alone is not sufficient to prevent stale data or instruction translations from surviving migration. Fix this by introducing a migration-specific helper that combines: - MM context invalidation (ASN rollover), - immediate per-CPU TLB invalidation (TBI), - synchronous cross-CPU shootdown when required. The helper is used only by migration/compaction paths to avoid changing global TLB semantics. Additionally, update flush_tlb_other(), pte_clear(), to use READ_ONCE()/WRITE_ONCE() for correct SMP memory ordering. This fixes observed crashes on both UP and SMP Alpha systems.

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. Record last changed materially (score, affected products, status or references).

References

Recent Out-of-bounds Write vulnerabilities

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