pyasn1 up to 0.6.3 BER/CER/DER Decoder decode RELATIVE-OID resource consumption

Summaryinfo

A vulnerability has been found in pyasn1 up to 0.6.3 and classified as problematic. This affects the function decode of the component BER/CER/DER Decoder. Performing a manipulation of the argument RELATIVE-OID results in resource consumption. This vulnerability is reported as CVE-2026-59885. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability, which was classified as problematic, was found in pyasn1 up to 0.6.3. This affects the function decode of the component BER/CER/DER Decoder. The manipulation of the argument RELATIVE-OID with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-59885 since 07/07/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 0.6.4 eliminates this vulnerability.

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Productinfo

Name

• pyasn1

Version

• 0.6.0
• 0.6.1
• 0.6.2
• 0.6.3

Website

• Product: https://github.com/pyasn1/pyasn1/

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