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pyasn1 CVE-2026-59886

| EUVDEUVD-2026-43738 HIGH
Uncontrolled Resource Consumption (CWE-400)
2026-07-14 GitHub_M GHSA-hm4w-wwcw-mr6r
Python Denial Of Service Pyasn1 Red Hat Suse
7.5
CVSS 3.1 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vuln.today AI
7.5 HIGH

Remote unauthenticated decoding of a tiny crafted value with no interaction yields availability-only impact; PR:N and C:N/I:N since only DoS occurs, AC:L as the payload is trivial to craft.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
7.5 HIGH
qualitative

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Lifecycle Timeline

4
Patch available
Jul 14, 2026 - 18:20 EUVD
Source Code Evidence Fetched
Jul 14, 2026 - 17:03 vuln.today
Analysis Generated
Jul 14, 2026 - 17:03 vuln.today
CVE Published
Jul 14, 2026 - 16:38 cve.org
HIGH 7.5

Blast Radius

ecosystem impact
† from your stack dependencies † transitive graph · vuln.today resolves 4-path depth
  • 21,501 pypi packages depend on pyasn1 (481 direct, 21,133 indirect)

Ecosystem-wide dependent count for version 0.6.4.

DescriptionCVE.org

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.

Articles & Coverage 1

News 14 New Python Vulnerabilities - 14 High Severity, 1 With POC Jul 15, 2026

AnalysisAI

Uncontrolled resource consumption in the pyasn1 Python ASN.1 library (versions prior to 0.6.4) lets remote attackers hang applications that decode untrusted BER/CER/DER data. A REAL value only a few bytes long can encode an enormous exponent; when the decoded univ.Real object is later printed, logged, compared, or converted via prettyPrint(), str(), int(), or float(), pyasn1 performs exact big-integer exponentiation that consumes excessive CPU and memory. There is no public exploit identified at time of analysis, but the network/no-auth/no-interaction, availability-only profile makes this a straightforward denial-of-service primitive; the issue is fixed in version 0.6.4.

Technical ContextAI

pyasn1 is a foundational, pure-Python ASN.1 encoder/decoder used as a transitive dependency across the Python ecosystem (X.509/PKI handling, LDAP clients such as ldap3, SNMP tooling, Kerberos and various crypto libraries). The root cause is CWE-400 (Uncontrolled Resource Consumption). ASN.1 REAL values in the binary (BER/CER/DER) encoding are stored as a (mantissa, base, exponent) triple, and the exponent field is variable-length, so a compact multi-byte exponent can represent an astronomically large power. The vulnerable code in pyasn1/type/univ.py computed float(mantissa * pow(base, exponent)) - materializing the full big integer via pow() before conversion. The fix short-circuits this: base-2 values use math.ldexp(), base-10 values raise OverflowError when the exponent exceeds sys.float_info.max_10_exp, and prettyPrint() now emits '<overflow>' instead of grinding through the exponentiation.

RemediationAI

Vendor-released patch: pyasn1 0.6.4 - upgrade to 0.6.4 or later (e.g. pip install --upgrade "pyasn1>=0.6.4"), which caps Real-to-float conversion via math.ldexp and OverflowError guards; the fix commit is e60c691cb91addb8fcefa2f537e85ede6fb1e886 and the advisory is GHSA-hm4w-wwcw-mr6r. If you cannot upgrade immediately, avoid invoking prettyPrint(), str(), float(), int(), comparison, or arithmetic on Real objects decoded from untrusted input (for example, do not log or repr() decoded ASN.1 structures that may contain REAL values) - the trade-off is losing diagnostic visibility on those objects. Where feasible, reject or size-limit inbound ASN.1 before decoding, or constrain schemas so the REAL universal type is not accepted from untrusted sources; note this only helps where your application controls the expected ASN.1 structure. Also audit and update transitive dependencies that pin an older pyasn1.

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Vendor StatusVendor

SUSE

Severity: Important
Product Status
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Python 3 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS Fixed
SUSE Linux Enterprise High Performance Computing 15 SP4 SUSE Linux Enterprise Module for Public Cloud 15 SP4 SUSE Linux Enterprise Server 15 SP4 SUSE Manager Proxy 4.3 SUSE Manager Retail Branch Server 4.3 SUSE Manager Server 4.3 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS Fixed

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CVE-2026-59886 vulnerability details – vuln.today
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