CVE-2026-59885
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk26th percentile - higher than 26% of all known CVEs
Summary
The pyasn1 library before version 0.6.4 has a quadratic time complexity in BER, CER, and DER decoders when processing OBJECT IDENTIFIER and RELATIVE-OID values with many arcs. A small crafted payload with many OID arcs causes excessive CPU consumption per decode() call, potentially leading to denial of service in applications processing untrusted ASN.1 data.
Risk Assessment
The organization is at risk of DoS attacks that can overload servers or applications processing ASN.1 data from untrusted sources, leading to service unavailability.
Recommendation
Immediately update the pyasn1 library to version 0.6.4 or later, which includes a fix for the quadratic complexity issue.
Other vulnerabilities in pyasn1
See all- CVE-2026-59886High
In pyasn1 prior to 0.6.4, the univ.Real type converts its mantissa, base, and exponent to a Python float using exact big-integer exponentiation. A short BER/CER/DER encoded REAL value can carry a very large exponent, causing excessive CPU and memory consumption and application hangs when prettyPrint(), str(), comparison, arithmetic, int(), or explicit float() is called on untrusted ASN.1 data.
- CVE-2026-59884High
The pyasn1 library before version 0.6.4 has a vulnerability in the BER decoder that does not limit the tag ID size when parsing long-form tags, allowing crafted input to force construction of an arbitrarily large integer with quadratic CPU cost and trigger unhandled ValueError exceptions in Python 3.11+.
- CVE-2026-30922High
The pyasn1 library prior to version 0.6.3 is vulnerable to a Denial of Service (DoS) attack due to uncontrolled recursion when decoding deeply nested ASN.1 structures. An attacker can craft a payload with thousands of nested SEQUENCE or SET tags with Indefinite Length markers, causing a stack overflow or memory exhaustion.
- CVE-2026-23490High
The pyasn1 library before version 0.6.2 is vulnerable to a Denial-of-Service attack causing memory exhaustion via malformed RELATIVE-OID with excessive continuation octets.
Original NVD description (English source)
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders process OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs, so a small crafted payload containing an OID with many arcs consumes excessive CPU per decode() call and can deny service to applications that decode untrusted ASN.1 data. The corresponding encoders have the same quadratic behavior when an application re-encodes previously decoded attacker-supplied values. This issue is fixed in version 0.6.4.