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Ubuntu 26.04 LTS pyasn1 Denial of Service Issues USN-8712

Linuxsecurity •LinuxSecurity Advisories • September 1, 2026

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Several security issues were fixed in pyasn1. Software Description: - pyasn1: ASN.1 library for Python Details: It was discovered that pyasn1 did not properly bound the size of long-form tag identifiers when parsing BER, CER, or DER encoded data. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59884) It was discovered that pyasn1 processed OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU resources, resulting in a denial of service. (CVE-2026-59885) It was discovered that pyasn1 incorrectly handled conversion of decoded REAL values to Python float types. An attacker could possibly use this issue to cause applications decoding untrusted ASN.1 data to consume excessive CPU and memory resources, re... Read the Full Advisory

Several security issues were fixed in pyasn1.

Software Description:

- pyasn1: ASN.1 library for Python

It was discovered that pyasn1 did not properly bound the size of long-form

tag identifiers when parsing BER, CER, or DER encoded data. An attacker

could possibly use this issue to cause applications decoding untrusted

ASN.1 data to consume excessive CPU resources, resulting in a denial of

service. (CVE-2026-59884)

It was discovered that pyasn1 processed OBJECT IDENTIFIER and RELATIVE-OID

values in quadratic time relative to the number of arcs. An attacker could

possibly use this issue to cause applications decoding untrusted ASN.1 data

to consume excessive CPU resources, resulting in a denial of service.

It was discovered that pyasn1 incorrectly handled conversion of decoded

REAL values to Python float types. An attacker could possibly use this

issue to cause applications decoding untrusted ASN.1 data to consume

excessive CPU and memory resources, re...

The problem can be corrected by updating your system to the following package versions: Ubuntu 26.04 LTS python3-pyasn1 0.6.3-1ubuntu0.1 Ubuntu 24.04 LTS python3-pyasn1 0.4.8-4ubuntu0.3 Ubuntu 22.04 LTS python3-pyasn1 0.4.8-1ubuntu0.3 In general, a standard system update will make all the necessary changes.

CVE-2026-59884, CVE-2026-59885, CVE-2026-59886

Ubuntu Security Notice USN-8712-1

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Denial of Service Vulnerabilities in pyasn1 Library Multiple vulnerabilities were discovered in the pyasn1 library, affecting applications that decode untrusted ASN.1 data. Specifically, CVE-2026-59884 allows for excessive CPU consumption due to improper size bounding of long-form tag identifiers. CVE-2026-59885 highlights quadratic processing time for OBJECT IDENTIFIER and RELATIVE-OID values, also leading to potential denial of service. Additionally, CVE-2026-59886 involves incorrect conversion of REAL values to Python float types, which can cause high CPU and memory usage. These vulnerabilities could be exploited by attackers to disrupt services. The affected systems include Ubuntu 26.04 LTS and earlier versions. Users are advised to update their systems to mitigate these risks. The vulnerabilities were published on July 14, 2026, and patches are available. 2 sources 46

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Ubuntu 26.04 LTS pyasn1 Denial of Service Issues USN-8712

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