CVE-2026-46107
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
In the Linux kernel's dm-thin module, a bug was found in the rebalance_children function where reference counts for grandchild nodes are not incremented when a shared child node is processed. This leads to metadata refcount underflow and 'unable to decrement block' errors.
Risk Assessment
The bug can cause filesystem instability and data integrity loss on dm-thin volumes. Block allocation errors may lead to metadata corruption and potential data unavailability.
Recommendation
Apply the latest Linux kernel patch containing the dm-thin fix. This update should be prioritized on systems using thin provisioning in Device Mapper.
Related vulnerabilities
- CVE-2026-71377Critical
Command argument injection vulnerability in Cosminexus Component Container. Allows an attacker to execute unauthorized system commands.
- CVE-2026-71376Critical
OS command injection vulnerability in Cosminexus Component Container. Allows an attacker to execute arbitrary commands on the server.
- CVE-2026-62645Critical
Vulnerability in Reyrolle 7SR5 exposes information through the web interface that can be used to calculate current and past session ID numbers. An attacker could bypass authentication and gain unauthorized access to the device.
- CVE-2026-50093Critical
Vulnerability in the OIS web module of Siveillance Control allows an attacker to upload arbitrary files to the server. Successful exploitation could allow an attacker to gain root access on the host system, potentially leading to full compromise of the OIS environment.
- CVE-2026-71374Critical
Deserialization of untrusted data vulnerability in Cosminexus Component Container. Could allow an attacker to execute arbitrary code or cause a crash.
- CVE-2026-86510Critical
The D-Link DIR-822A router version A_101 has a vulnerability in the tunnel_set_params function of the L2TP Control Message Parser component, leading to an out-of-bounds write. The attack can be launched remotely, and the exploit has been publicly disclosed.
- CVE-2026-86509Critical
The D-Link DIR-895L router version A1_102b07 has a vulnerability in the sendOffer/sendACK functions of the file udhcpcd/serverpacket.c in the udhcpcd component, causing a stack-based buffer overflow. The attack can only be performed within the local network, and the exploit has been published.
- CVE-2026-76969Critical
The @sap/cds-mtxs NPM library does not perform sufficient checks on certain functionality used in multitenant CAP applications with extensibility enabled. An unauthenticated attacker could send specially crafted requests to obtain sensitive credentials and abuse them to replace or delete tenant data. Successful exploitation can result in a high impact on availability and integrity of the application, and partial impact on confidentiality of business data.
- CVE-2026-66768Critical
SAP GUI for Java does not correctly enforce the trust level policy for certain functions invoked from a connected backend system. A low-privileged attacker could exploit this weakness by manipulating a connected backend system to trigger affected functionality. This could allow arbitrary command execution on the victim's machine, leading to a high impact on confidentiality, integrity, and availability.
- CVE-2026-58240Critical
SAP NetWeaver Message Server does not sufficiently validate the authenticity of internal application server components during registration. An unauthenticated attacker with network access could register an unauthorized component and potentially perform unauthorized actions, resulting in high impact on confidentiality, integrity, and availability.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: dm-thin: fix metadata refcount underflow There's a bug in dm-thin in the function rebalance_children. If the internal btree node has one entry, the code tries to copy all btree entries from the node's child to the node itself and then decrement the child's reference count. If the child node is shared (it has reference count > 1), we won't free it, so there would be two pointers to each of the grandchildren nodes. But the reference counts of the grandchildren is not increased, thus the reference count doesn't match the number of pointers that point to the grandchildren. This results in "device mapper: space map common: unable to decrement block" errors. Fix this bug by incrementing reference counts on the grandchildren if the btree node is shared.

