CyberSecBulletin
CVE-2026-43304NVD status: Modified

Linux: Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2026-43304 is a critical-severity stack-based buffer overflow vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 6405e8c680974bb74e2c98d5249fb52c7b12a6c6, 8d745d38c88ecbed95f6b2b39857bf89f35a3244, e1dc45d97975f9db65694d234fbddf1915176e16 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 0.61% chance of exploitation within 30 days, which is low compared with other CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Linux to 6405e8c680974bb74e2c98d5249fb52c7b12a6c6 or 8d745d38c88ecbed95f6b2b39857bf89f35a3244 or e1dc45d97975f9db65694d234fbddf1915176e16 or 1b275bd49e58752efb83767a5d1aed41356c5e64, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.15.202 or 6.1.165 or 6.6.128 or 6.12.75, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxcd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, 6405e8c680974bb74e2c98d5249fb52c7b12a6c6; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, 8d745d38c88ecbed95f6b2b39857bf89f35a3244; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, e1dc45d97975f9db65694d234fbddf1915176e16; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, 1b275bd49e58752efb83767a5d1aed41356c5e64; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, c1a0f5f1e5e7e98c36a362ec3d1fcfd9932931ed; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, d82467c07b03a27c3c5469b62bb3b726305a80bb; cd1a677cad994021b19665ed476aea63f5d54f31 up to, but not including, ac431d597a9bdfc2ba6b314813f29a6ef2b4a3bf; 5.116405e8c680974bb74e2c98d5249fb52c7b12a6c6, 8d745d38c88ecbed95f6b2b39857bf89f35a3244, e1dc45d97975f9db65694d234fbddf1915176e16, 1b275bd49e58752efb83767a5d1aed41356c5e64, c1a0f5f1e5e7e98c36a362ec3d1fcfd9932931ed, d82467c07b03a27c3c5469b62bb3b726305a80bb
LinuxLinux Kernel5.11 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 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, 6.19.65.15.202, 6.1.165, 6.6.128, 6.12.75, 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
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
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:N/AC:L/PR:N/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: libceph: define and enforce CEPH_MAX_KEY_LEN When decoding the key, verify that the key material would fit into a fixed-size buffer in process_auth_done() and generally has a sane length. The new CEPH_MAX_KEY_LEN check replaces the existing check for a key with no key material which is a) not universal since CEPH_CRYPTO_NONE has to be excluded and b) doesn't provide much value since a smaller than needed key is just as invalid as no key -- this has to be handled elsewhere anyway.

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

The underlying weakness: Stack-based Buffer Overflow

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

How developers prevent this class of flaw

  • 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.
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Implement and perform bounds checking on input.

More Stack-based Buffer Overflow vulnerabilities (CWE-121)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Stack-based Buffer Overflow vulnerabilities

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