USN-9011-1: pyasn1 vulnerabilities
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. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (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. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (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, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-59886)
It was discovered that pyasn1 incorrectly handled tracking component types when decoding containers without a schema. 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. This issue only affected Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS, Ubuntu 26.04 LTS, and Ubuntu 26.10. (CVE-2026-119194)
It was discovered that pyasn1 processed fragmented constructed strings and indefinite-length ANY values in quadratic time. 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. This issue was only addressed in Ubuntu 26.04 LTS and Ubuntu 26.10. (CVE-2026-119195)
It was discovered that pyasn1 processed fragmented constructed BIT STRING values in quadratic time. 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-2026-119196)
It was discovered that pyasn1 processed binary-encoded REAL values with large mantissas in quadratic time. 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-2026-119197)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.1.7-1ubuntu2.1+esm2 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.1.9-1ubuntu0.1~esm2 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.4.2-3ubuntu0.18.04.1~esm2 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.4.2-3ubuntu0.20.04.1~esm2 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.4.8-1ubuntu0.4 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.4.8-4ubuntu0.4 - Upgrade
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ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.6.4-1ubuntu0.1 - Upgrade
Upgrade
ubuntu/pyasn1to a version that resolves this vulnerability.Fixed in 0.6.3-1ubuntu0.2
Event History
Child vulnerabilities
Contains the following vulnerabilities.
Frequently Asked Questions
Which systems are affected?
The issues affect pyasn1 on Ubuntu 14.04 LTS, Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. Other Ubuntu releases are not identified as affected in the provided advisory data.
What must an attacker be able to do to trigger these issues?
An attacker needs to cause an application to decode untrusted ASN.1 data. The affected parsing paths include BER, CER, and DER encoded data, as well as OBJECT IDENTIFIER, RELATIVE-OID, and REAL values.
What is the practical impact?
Specially crafted input can cause excessive CPU consumption, and the REAL-value conversion issue can also consume excessive memory. The stated impact is denial of service against applications that decode the attacker-controlled data.