CVE-2026-59886

High

Description

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded objects. This issue is fixed in version 0.6.4.

SeverityHigh

CVSS7.5

Exploit probability—

ProductPyasn1

PublishedJul 14, 2026

First seenJul 14, 2026

Weakness typeCWE-400Uncontrolled resource consumption CWE-770Allocation of resources without limits

How to fix

Update

pyasn1 pyasn10.6.4 or later
pyasn10.6.4 or later

Affected products

Product	Affected versions	Fixed in
pyasn1 pyasn1	v < 0.6.4	0.6.4
pyasn1PyPI	v < 0.6.4	0.6.4

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