🟠 High | Source: Microsoft Security Response Center
A vulnerability in the pyasn1 Python library allows an attacker to trigger excessive CPU consumption by supplying specially crafted OBJECT IDENTIFIER or RELATIVE-OID data, leading to a denial of service. The quadratic time complexity means that as input size grows, processing time grows disproportionately, making it easy to exhaust resources with relatively small payloads. This is particularly relevant for Azure services and applications that rely on pyasn1 for parsing ASN.1-encoded data, such as those handling certificates or SNMP messages.
Security Architect’s Take: Identify any Azure workloads or application dependencies that use pyasn1 for ASN.1 parsing — particularly those processing untrusted external input such as certificates or network protocol data — and prioritise updating pyasn1 to a patched version. Additionally, consider adding input size validation or rate limiting at ingress points to mitigate exploitation risk while patching is under way.
Original advisory: CVE-2026-59885 pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service