CVE-2026-23490
Published: 16 January 2026
Summary
CVE-2026-23490 is a high-severity Allocation of Resources Without Limits or Throttling (CWE-770) vulnerability in Pyasn1 Pyasn1. Its CVSS base score is 7.5 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Application or System Exploitation (T1499.004); ranked at the 6.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
This control implements explicit throttling on session allocation, addressing the weakness of allocating resources without limits.
Plan testing exercises resource allocation limits and throttling during simulated failures, directly addressing weaknesses that allow unbounded resource use.
Contingency plan updates ensure recovery strategies address unbounded resource allocation, making it harder for attackers to exploit lack of throttling to cause prolonged outages.
Provides continuity when unbounded resource allocation at the primary site leads to exhaustion and downtime.
Alternate services allow operations to continue when primary allocation of resources lacks limits or throttling.
Explicit planning of security-related actions requires defining limits, windows, and resource allocations, making allocation without throttling far less likely.
Measures of performance include tracking allocation behavior and throttling effectiveness, reducing the window for resource exhaustion attacks.
Imposes an inactivity-based limit on network resource allocation, throttling the number of concurrently held connections.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Direct match to application exploitation causing endpoint DoS via unbounded memory allocation from malformed input.
NVD Description
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.2, a Denial-of-Service issue has been found that leads to memory exhaustion from malformed RELATIVE-OID with excessive continuation octets. This vulnerability is fixed in 0.6.2.
Deeper analysisAI
CVE-2026-23490 is a denial-of-service vulnerability in pyasn1, a generic ASN.1 library for Python, affecting versions prior to 0.6.2. The issue arises from processing a malformed RELATIVE-OID with excessive continuation octets, leading to memory exhaustion. Published on 2026-01-16, it carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) and is categorized under CWE-770 (Allocation of Resources Without Limits or Throttling).
An unauthenticated attacker can exploit this vulnerability remotely over the network with low attack complexity and no user interaction required. By supplying specially crafted input to an application using the vulnerable pyasn1 library, the attacker can trigger unbounded memory allocation, resulting in high-impact denial of service that exhausts system resources and disrupts service availability.
The vulnerability is addressed in pyasn1 version 0.6.2, where the fix is implemented via commit 3908f144229eed4df24bd569d16e5991ace44970. Official resources include the GitHub security advisory GHSA-63vm-454h-vhhq, release notes for v0.6.2, and a Debian LTS announcement detailing mitigation for affected distributions. Security practitioners should prioritize upgrading to the patched version.
Details
- CWE(s)