CVE-2026-23455
Linux Kernel out-of-bounds read
- Published3 Apr 2026
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0
- https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4
- https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111
- https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710
- https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8
- https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b
References
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0
- https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4
- https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111
- https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710
- https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8
- https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b
- https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66
- https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-23455 being actively exploited?
CVE-2026-23455 is not in the CISA KEV catalog. Its EPSS exploit probability is 1.34%.
How severe is CVE-2026-23455?
CVE-2026-23455 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 1.34% probability of exploitation.
Which products are affected by CVE-2026-23455?
Affected products include Linux Kernel.
How do I fix CVE-2026-23455?
Upgrade affected software to a fixed version, for example Linux Kernel 5.10.253 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-23455 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.