CVE-2026-121505
Description
A flaw was found in NTPsec. A malicious Network Time Security Key Exchange (NTS-KE) server can cause information disclosure by sending a response record with a declared length exceeding the data received. This triggers an out-of-bounds read in the client response parser, allowing the server to retrieve sensitive stack memory, such as internal pointers that weaken Address Space Layout Randomization (ASLR), which the client sends back in cleartext.
Statement
This vulnerability is rated with a Low severity because exploitation requires an attacker to operate or compromise a designated upstream NTS-KE time server, limiting the attack surface to scenarios where a client connects to an untrusted endpoint. Red Hat Enterprise Linux does not include NTPsec in core repositories, relying on chrony as the default time synchronization mechanism. On systems where NTPsec is obtained from community channels, the impact is confined to partial client memory disclosure with no capability for remote code execution or disruption of system availability.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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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