CVE-2026-104592
Description
A flaw was found in libosmocore. An out-of-bounds read vulnerability in the Cell Broadcast Service Protocol (CBSP) message decoder allows a remote attacker to cause a Denial of Service (DoS). By sending specially crafted CBSP WRITE-REPLACE messages, an attacker can trigger an invalid memory read, causing the service to crash.
Statement
This vulnerability is rated with an Important severity because an unauthenticated network adversary can cause complete service unavailability remotely without requiring user interaction. Network services utilizing the protocol parser handle incoming broadcast communication directly, making unexpected memory access result in a crash. Red Hat Enterprise Linux does not distribute or support libosmocore, restricting any potential impact to community distributions such as Fedora.
Mitigation
--- CME Mitigation Guidance (2026-11-02) ---
Disclaimer: The following mitigation solutions are provided as a courtesy, pending the application of an official patch. This content was generated utilizing AI tools in conjunction with data from https://cmetaxonomy.org. Customers are advised to independently evaluate and test these temporary mitigations within their own infrastructure.
The highest-value action is to enforce bounds checking on the CBSP page count field in cbsp_dec_write_repl() before using it as a loop bound over fixed-size array buffers: upgrade to the fixed Libosmocore builds, which reject CBSP messages with a page count less than 1 or greater than 16 by returning -EINVAL, closing crafted CBSP WRITE-REPLACE message with page count exceeding 16. Until patched, this is a concern on Services processing Cell Broadcast Service Protocol (CBSP) messages using libosmocore, so Restrict untrusted network access to CBSP protocol ports and services parsing Cell Broadcast Service Protocol messages with libosmocore. These controls limit blast radius and contain exploitation, but they do not fix the underlying out-of-bounds read defect — apply the upstream patch to fully remediate.
Highest-impact CME: CME-1311 Input Size and Quantity Bounds Enforcement (high)
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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