CyberSecBulletin
CVE-2026-45999NVD status: Modified

Linux: Integer Underflow (Wrap or Wraparound)

Published Updated By the CyberSecBulletin desk

CVE-2026-45999 is a high-severity integer underflow (wrap or wraparound) 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 unauthenticated attacker, but only if a user takes part, for example by opening a link or file. The record lists versions 778acd52e9497806fbd2cea7f770c41d6850fc48, 118ff71ff09ebaf323a09af9e911517321a299f4, 43a878639b90e9721ffa5eb616a7e6d8454adef3 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 778acd52e9497806fbd2cea7f770c41d6850fc48 or 118ff71ff09ebaf323a09af9e911517321a299f4 or 43a878639b90e9721ffa5eb616a7e6d8454adef3 or f1374fa6e57fd836623668d782ded9244cfd2938, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.140 or 6.12.88 or 6.18.30 or 7.0.4, whichever matches your release line, or a later version.
  3. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux598162d050801e556750defff4ddab499e5d76ed up to, but not including, 778acd52e9497806fbd2cea7f770c41d6850fc48; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, 118ff71ff09ebaf323a09af9e911517321a299f4; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, 43a878639b90e9721ffa5eb616a7e6d8454adef3; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, f1374fa6e57fd836623668d782ded9244cfd2938; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, c9ce18e6bb2c467ec85756dc7989b547b7584fee; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, bbbbb3f0d7864238a8da2a94cd6ec013fee06a2e; 598162d050801e556750defff4ddab499e5d76ed up to, but not including, 21e161de2dc660b1bb70ef5b156ab8e6e1cca3ab; 5.13778acd52e9497806fbd2cea7f770c41d6850fc48, 118ff71ff09ebaf323a09af9e911517321a299f4, 43a878639b90e9721ffa5eb616a7e6d8454adef3, f1374fa6e57fd836623668d782ded9244cfd2938, c9ce18e6bb2c467ec85756dc7989b547b7584fee, bbbbb3f0d7864238a8da2a94cd6ec013fee06a2e
LinuxLinux Kernel5.13 up to, but not including, 6.6.140; 6.7 up to, but not including, 6.12.88; 6.13 up to, but not including, 6.18.30; 6.19 up to, but not including, 7.0.46.6.140, 6.12.88, 6.18.30, 7.0.4

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
NoneNo account or login is needed.
User interaction
RequiredA user must take an action such as opening a file or link.
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:N/UI:R/S:U/C:H/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: erofs: fix unsigned underflow in z_erofs_lz4_handle_overlap() Some crafted images can have illegal (!partial_decoding && m_llen < m_plen) extents, and the LZ4 inplace decompression path can be wrongly hit, but it cannot handle (outpages < inpages) properly: "outpages - inpages" wraps to a large value and the subsequent rq->out[] access reads past the decompressed_pages array. However, such crafted cases can correctly result in a corruption report in the normal LZ4 non-inplace path. Let's add an additional check to fix this for backporting. Reproducible image (base64-encoded gzipped blob): H4sIAJGR12kCA+3SPUoDQRgG4MkmkkZk8QRbRFIIi9hbpEjrHQI5ghfwCN5BLCzTGtLbBI+g dilSJo1CnIm7GEXFxhT6PDDwfrs73/ywIQD/1ePD4r7Ou6ETsrq4mu7XcWfj++Pb58nJU/9i PNtbjhan04/9GtX4qVYc814WDqt6FaX5s+ZwXXeq52lndT6IuVvlblytLMvh4Gzwaf90nsvz 2DF/21+20T/ldgp5s1jXRaN4t/8izsy/OUB6e/Qa79r+JwAAAAAAAL52vQVuGQAAAP6+my1w ywAAAAAAAADwu14ATsEYtgBQAAA= $ mount -t erofs -o cache_strategy=disabled foo.erofs /mnt $ dd if=/mnt/data of=/dev/null bs=4096 count=1

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

The underlying weakness: Integer Underflow (Wrap or Wraparound)

The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Integer Underflow (Wrap or Wraparound) vulnerabilities

Spotted an error? Tell us.