CVE-2026-23490

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.

What this means for your business

It affects Pyasn1. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
FIRST's prediction model gives it a 0.8% chance of attack attempts being seen in the next 30 days, ranking above 53% of all known flaws.

What to do

1Check whether your company or your suppliers run Pyasn1, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 7.5 (v3.1)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness: CWE-770
Assigned by: security-advisories@github.com

Dates

Published: 2026-01-16
Last modified: 2026-09-09
Sources: NVD

Affected products

Pyasn1 Pyasn1- 0.6.2
Debian Debian Linux11.0

As listed in the NVD configuration data. Not a statement about your estate.