Heap Buffer Vulnerability in Rsyslog's imhttp Module Impacts Log Processing

CVE-2026-55556

What is CVE-2026-55556?

The vulnerability in Rsyslog's imhttp module, affecting versions 8.2110.0 through 8.2604.0, arises from the parse_auth_header function, which allocates a zero-byte heap buffer due to an oversized HTTP Basic Authorization value. This flaw can be exploited by an unauthenticated remote attacker to send an oversized encoded credential, resulting in potential memory corruption. Although a process crash can disrupt log collection, the risk of arbitrary code execution has not been demonstrated. Users should update to version 8.2604.0 or later to mitigate this vulnerability.

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