pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.

An update of the python3 package has been released.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2026-3836 advisory.

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER     codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID     size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing     quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any     application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
    (CVE-2026-59884)

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders process     OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs, so a small     crafted payload containing an OID with many arcs consumes excessive CPU per decode() call and can deny     service to applications that decode untrusted ASN.1 data. The corresponding encoders have the same     quadratic behavior when an application re-encodes previously decoded attacker-supplied values. This issue     is fixed in version 0.6.4. (CVE-2026-59885)

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa,     base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER     encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through     prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU     and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded     objects. This issue is fixed in version 0.6.4. (CVE-2026-59886)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2000 advisory.

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER     codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID     size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing     quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any     application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
    (CVE-2026-59884)

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders process     OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs, so a small     crafted payload containing an OID with many arcs consumes excessive CPU per decode() call and can deny     service to applications that decode untrusted ASN.1 data. The corresponding encoders have the same     quadratic behavior when an application re-encodes previously decoded attacker-supplied values. This issue     is fixed in version 0.6.4. (CVE-2026-59885)

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa,     base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER     encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through     prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU     and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded     objects. This issue is fixed in version 0.6.4. (CVE-2026-59886)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 host has a package installed that is affected by multiple vulnerabilities as referenced in the SUSE-SU-2026:3238-1 advisory.

    - CVE-2026-59884: BER/CER/DER decoder denial of service via unbounded long-form tag IDs (bsc#1271464).
    - CVE-2026-59885: quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of     service       (bsc#1271465).
    - CVE-2026-59886: uncontrolled resource consumption when converting decoded REAL values (bsc#1271466).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote openSUSE 16 host has a package installed that is affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:21392-1 advisory.

    - CVE-2026-59884: BER/CER/DER decoder denial of service via unbounded long-form tag IDs (bsc#1271464).
    - CVE-2026-59885: quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of     service       (bsc#1271465).
    - CVE-2026-59886: uncontrolled resource consumption when converting decoded REAL values (bsc#1271466).

Tenable has extracted the preceding description block directly from the SUSE security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER
    codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID
    size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing
    quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any
    application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
    (CVE-2026-59884)

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER     codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID     size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing     quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any     application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
    (CVE-2026-59884)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
333264	Photon OS 5.0: Python3 PHSA-2026-5.0-92-0945	Nessus	PhotonOS Local Security Checks	Local	high
332047	Amazon Linux 2 : python-pyasn1, --advisory ALAS2-2026-3836 (ALAS-2026-3836)	Nessus	Amazon Linux Local Security Checks	Local	high
332035	Amazon Linux 2023 : python3-pyasn1, python3-pyasn1-modules (ALAS2023-2026-2000)	Nessus	Amazon Linux Local Security Checks	Local	high
330310	SUSE SLED15 / SLES15 Security Update : python-pyasn1 (SUSE-SU-2026:3238-1)	Nessus	SuSE Local Security Checks	Local	high
329306	openSUSE 16 Security Update : python-pyasn1 (openSUSE-SU-2026:21392-1)	Nessus	SuSE Local Security Checks	Local	high
445100	SCA: security update for pyasn1 (GHSA-m4p7-r5rc-7g4j)	Tenable Cloud Security	SCA Checks	Local	high
445100	SCA: security update for pyasn1 (GHSA-m4p7-r5rc-7g4j)	Tenable Self-Hosted Container Security	SCA Checks	Local	high
327213	Linux Distros Unpatched Vulnerability : CVE-2026-59884	Nessus	Misc.	Local	high

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