Home / mailings [USN-9011-1] pyasn1 vulnerabilities
Posted on 09 November 2026
Ubuntu Security==========================================================================Ubuntu Security Notice USN-9011-1
November 09, 2026
pyasn1 vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 26.10
- Ubuntu 26.04 LTS
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS
- Ubuntu 14.04 LTS
Summary:
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. 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)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 26.10
python3-pyasn1 0.6.4-1ubuntu0.1
Ubuntu 26.04 LTS
python3-pyasn1 0.6.3-1ubuntu0.2
Ubuntu 24.04 LTS
python3-pyasn1 0.4.8-4ubuntu0.4
Ubuntu 22.04 LTS
python3-pyasn1 0.4.8-1ubuntu0.4
Ubuntu 20.04 LTS
pypy-pyasn1 0.4.2-3ubuntu0.20.04.1~esm2
Available with Ubuntu Pro
python-pyasn1 0.4.2-3ubuntu0.20.04.1~esm2
Available with Ubuntu Pro
python3-pyasn1 0.4.2-3ubuntu0.20.04.1~esm2
Available with Ubuntu Pro
Ubuntu 18.04 LTS
pypy-pyasn1 0.4.2-3ubuntu0.18.04.1~esm2
Available with Ubuntu Pro
python-pyasn1 0.4.2-3ubuntu0.18.04.1~esm2
Available with Ubuntu Pro
python3-pyasn1 0.4.2-3ubuntu0.18.04.1~esm2
Available with Ubuntu Pro
Ubuntu 16.04 LTS
pypy-pyasn1 0.1.9-1ubuntu0.1~esm2
Available with Ubuntu Pro
python-pyasn1 0.1.9-1ubuntu0.1~esm2
Available with Ubuntu Pro
python3-pyasn1 0.1.9-1ubuntu0.1~esm2
Available with Ubuntu Pro
Ubuntu 14.04 LTS
python-pyasn1 0.1.7-1ubuntu2.1+esm2
Available with Ubuntu Pro
python3-pyasn1 0.1.7-1ubuntu2.1+esm2
Available with Ubuntu Pro
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-9011-1
CVE-2026-119194, CVE-2026-119195, CVE-2026-119196, CVE-2026-119197,
CVE-2026-59884, CVE-2026-59885, CVE-2026-59886
Package Information:
https://launchpad.net/ubuntu/+source/pyasn1/0.6.4-1ubuntu0.1
https://launchpad.net/ubuntu/+source/pyasn1/0.6.3-1ubuntu0.2
https://launchpad.net/ubuntu/+source/pyasn1/0.4.8-4ubuntu0.4
https://launchpad.net/ubuntu/+source/pyasn1/0.4.8-1ubuntu0.4
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