pyasn1 up to 0.6.4 Binary Real Decoding RealPayloadDecoder.valueDecoder resource consumption

Summaryinfo

A vulnerability was found in pyasn1 up to 0.6.4. It has been rated as problematic. Affected is the function RealPayloadDecoder.valueDecoder of the component Binary Real Decoding. Performing a manipulation results in resource consumption. This vulnerability is reported as CVE-2026-119197. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in pyasn1 up to 0.6.4. It has been classified as problematic. This affects the function RealPayloadDecoder.valueDecoder of the component Binary Real Decoding. The manipulation with an unknown input leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-119197 since 10/29/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 374248 (Linux Distros Unpatched Vulnerability : CVE-2026-119197), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.6.5 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (374248). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Name

• pyasn1

Version

• 0.6.0
• 0.6.1
• 0.6.2
• 0.6.3
• 0.6.4

Website

• Product: https://github.com/pyasn1/pyasn1/

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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