CVE-2026-119197

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, binary REAL decoding builds a large mantissa one octet at a time by shifting a growing integer and slicing the remaining byte string. Attacker-controlled ASN.1 includes a binary-encoded REAL with a large mantissa and reaches BER, CER, or DER decode(), with or without a schema containing REAL. RealPayloadDecoder.valueDecoder repeatedly performs a left shift, OR, and suffix copy for every mantissa octet, making decode time quadratic in mantissa length. A comparatively small REAL value can hold a decoding worker on one CPU core for seconds or longer and cause availability loss. This issue is fixed in version 0.6.5.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/pyasn1/pyasn1/commit/ce3ec3390784780a530047e0e77be5ff457636a4
https://github.com/pyasn1/pyasn1/pull/132
https://github.com/pyasn1/pyasn1/releases/tag/v0.6.5
https://github.com/pyasn1/pyasn1/security/advisories/GHSA-mm57-4v3p-rchx

Configurations

No configuration.

History

29 Oct 2026, 20:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-29 20:17

Updated : 2026-10-30 17:18

NVD link : CVE-2026-119197

Mitre link : CVE-2026-119197

CVE.ORG link : CVE-2026-119197

JSON object : View

Products Affected

No product.

CWE

CWE-407

Inefficient Algorithmic Complexity

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