CVE-2026-59885Network attack vector

Service interruption via quadratic OID arc accumulation

Published Jul 14, 2026 · Updated Jul 14, 2026

Algorithmic complexity in pyasn1 before 0.6.4 allows remote attackers to interrupt services via crafted ASN.1 OID values. The BER decoder repeatedly concatenates immutable tuples while accumulating OBJECT IDENTIFIER and RELATIVE-OID arcs, and the encoder does the same for output octets, making processing quadratic in the arc count. Reachability requires an application to decode untrusted BER, CER, or DER data, or to re-encode attacker-supplied decoded values; each small payload can consume seconds of CPU.

CVSS severity7.5
High
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Algorithmic complexity in pyasn1 before 0.6.4 allows remote attackers to interrupt services via crafted ASN.1 OID values. The BER decoder repeatedly concatenates immutable tuples while accumulating OBJECT IDENTIFIER and RELATIVE-OID arcs, and the encoder does the same for output octets, making processing quadratic in the arc count. Reachability requires an application to decode untrusted BER, CER, or DER data, or to re-encode attacker-supplied decoded values; each small payload can consume seconds of CPU.

The record

CVE
CVE-2026-59885
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
pyasn1
Product
pyasn1
Classifications
CWE-400, CWE-407, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.6.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

pyasn1 · pyasn1version=< 0.6.4

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
CWE-407Inefficient Algorithmic Complexity
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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