CyberSecBulletin
CVE-2026-43329NVD status: Modified

Linux: Heap-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-43329 is a high-severity heap-based buffer overflow 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 ead66c77303f760f6c30be96e2e20d5a77cef614, fe9018d3e94329f1951b00805a8640bc06f56ead, 5382bb03e9c33b089d60788478b922a2dca284cc 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 ead66c77303f760f6c30be96e2e20d5a77cef614 or fe9018d3e94329f1951b00805a8640bc06f56ead or 5382bb03e9c33b089d60788478b922a2dca284cc or 57c78bd2e2dd08897acd35b2bf8bcef322e36f5e, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.203 or 6.1.168 or 6.6.134 or 6.12.81, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxc29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, ead66c77303f760f6c30be96e2e20d5a77cef614; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, fe9018d3e94329f1951b00805a8640bc06f56ead; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, 5382bb03e9c33b089d60788478b922a2dca284cc; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, 57c78bd2e2dd08897acd35b2bf8bcef322e36f5e; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, 504c9456699dcf4d15195ef34a0fa94a80bfc877; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, 879959a7a2be814dd57568655eafa3d8f4d0309e; c29f74e0df7a02b8303bcdce93a7c0132d62577a up to, but not including, 76522fcdbc3a02b568f5d957f7e66fc194abb893; 5.5ead66c77303f760f6c30be96e2e20d5a77cef614, fe9018d3e94329f1951b00805a8640bc06f56ead, 5382bb03e9c33b089d60788478b922a2dca284cc, 57c78bd2e2dd08897acd35b2bf8bcef322e36f5e, 504c9456699dcf4d15195ef34a0fa94a80bfc877, 879959a7a2be814dd57568655eafa3d8f4d0309e
Red HatRed Hat Enterprise Linux 10Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 10.0 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update ServiceNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9Not specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP SolutionsNot specified in the recordNot stated
Red HatRed Hat Enterprise Linux 9.6 Extended Update SupportNot specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.12Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.13Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.14Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.15Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.16Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.17Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.18Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.19Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.20Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.21Not specified in the recordNot stated
Red HatRed Hat OpenShift Container Platform 4.22Not specified in the recordNot stated

Version data comes from the organisation that assigned the CVE; 4 further products are omitted here. 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.

Scoring systemScoreSeverityScored by
CVSS 3.17.8HighCNA
CVSS 3.17.8HighCNA

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: strictly check for maximum number of actions The maximum number of flowtable hardware offload actions in IPv6 is: * ethernet mangling (4 payload actions, 2 for each ethernet address) * SNAT (4 payload actions) * DNAT (4 payload actions) * Double VLAN (4 vlan actions, 2 for popping vlan, and 2 for pushing) for QinQ. * Redirect (1 action) Which makes 17, while the maximum is 16. But act_ct supports for tunnels actions too. Note that payload action operates at 32-bit word level, so mangling an IPv6 address takes 4 payload actions. Update flow_action_entry_next() calls to check for the maximum number of supported actions. While at it, rise the maximum number of actions per flow from 16 to 24 so this works fine with IPv6 setups.

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

The underlying weakness: Heap-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the heap.

How developers prevent this class of flaw

  • Pre-design: Use a language or compiler that performs automatic bounds checking.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • 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 Heap-based Buffer Overflow vulnerabilities (CWE-122)

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 Heap-based Buffer Overflow vulnerabilities

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