CVE-2026-59886Network attack vectorHinoki check available

Application hang via oversized REAL exponent conversion

Published Jul 14, 2026 · Updated Jul 14, 2026

Resource exhaustion in pyasn1 before 0.6.4 allows remote attackers to hang applications through a crafted ASN.1 REAL value. The Real.float method multiplies the mantissa by the base raised to an attacker-controlled exponent, materializing an enormous integer before float conversion. Exploitation requires an application to decode an untrusted BER, CER, or DER REAL and then print, log, compare, or otherwise convert it; decoding alone does not trigger the hang.

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

What happened

Resource exhaustion in pyasn1 before 0.6.4 allows remote attackers to hang applications through a crafted ASN.1 REAL value. The Real.float method multiplies the mantissa by the base raised to an attacker-controlled exponent, materializing an enormous integer before float conversion. Exploitation requires an application to decode an untrusted BER, CER, or DER REAL and then print, log, compare, or otherwise convert it; decoding alone does not trigger the hang.

The record

CVE
CVE-2026-59886
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
pyasn1
Product
pyasn1
Classifications
CWE-770, CWE-400, 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-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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