pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE` (`0x30`) or `SET` (`0x31`) tags with "Indefinite Length" (`0x80`) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all available memory (OOM), crashing the host application. This is a distinct vulnerability from CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490 (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this specific issue.

The remote Debian 13 host has packages installed that are affected by a vulnerability as referenced in the dsa-6194 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6194-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     April 03, 2026                        https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : pyasn1     CVE ID         : CVE-2026-30922     Debian Bug     : 1131371

    It was discovered that pyasn1, a generic ASN.1 library for Python, is     prone to a denial of service vulnerability when decoding ASN.1 data with     deeply nested structures.

    For the oldstable distribution (bookworm), this problem has been fixed     in version 0.4.8-3+deb12u2.

    For the stable distribution (trixie), this problem has been fixed in     version 0.6.1-1+deb13u2.

    We recommend that you upgrade your pyasn1 packages.

    For the detailed security status of pyasn1 please refer to its security     tracker page at:
    https://security-tracker.debian.org/tracker/pyasn1

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

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

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

It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3215 advisory.

    pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a     Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply     nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE`     (`0x30`) or `SET` (`0x31`) tags with Indefinite Length (`0x80`) markers. This forces the decoder to     recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all     available memory (OOM), crashing the host application. This is a distinct vulnerability from     CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490     (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this     specific issue. (CVE-2026-30922)

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

Note that Nessus has not tested for this issue 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 a vulnerability as referenced in the SUSE-SU-2026:1158-1 advisory.

    - CVE-2026-30922: Denial of Service via Unbounded Recursion (bsc#1259803).

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

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

The remote Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8134-1 advisory.

    It was discovered that pyasn1 could exhaust system resources when attempting to decode a malformed     certificate. An attacker could possibly use this to cause a denial of service. (CVE-2026-23490)

    Kevin Tu discovered that pyasn1 could exhaust system resources via uncontrolled recursion when attempting     to decode malicously-crafted certificates. An attacker could possibly use this to cause a denial of     service. (CVE-2026-30922)

Tenable has extracted the preceding description block directly from the Ubuntu 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 Ubuntu 22.04 LTS / 24.04 LTS / 25.10 host has packages installed that are affected by a vulnerability as referenced in the USN-8129-1 advisory.

    It was discovered that pyasn1 incorrectly handled recursion when decoding ASN.1 data. An attacker could     use this issue to cause pyasn1 to consume resources, leading to a denial of service.

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

Note that Nessus has not tested for this issue 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 a vulnerability as referenced in the openSUSE- SU-2026:20418-1 advisory.

    This update for python-pyasn1 fixes the following issue:

    - CVE-2026-30922: Denial of Service via Unbounded Recursion (bsc#1259803).

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

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

The remote SUSE Linux SLED15 / SLED_SAP15 / SLES15 / SLES_SAP15 / openSUSE 15 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2026:1075-1 advisory.

    - CVE-2026-30922: Denial of Service via Unbounded Recursion (bsc#1259803).

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

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

The remote SUSE Linux SLES12 host has packages installed that are affected by a vulnerability as referenced in the SUSE- SU-2026:1076-1 advisory.

    - CVE-2026-30922: Denial of Service via Unbounded Recursion (bsc#1259803).

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

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

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 0.6.3, the `pyasn1` library is vulnerable to a     Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply     nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE`     (`0x30`) or `SET` (`0x31`) tags with Indefinite Length (`0x80`) markers. This forces the decoder to     recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all     available memory (OOM), crashing the host application. This is a distinct vulnerability from     CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490     (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this     specific issue. (CVE-2026-30922)

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

ID	Name	Product	Family	Severity
304943	Debian dsa-6194 : python-pyasn1-doc - security update	Nessus	Debian Local Security Checks	high
304577	Amazon Linux 2 : python-pyasn1, --advisory ALAS2-2026-3215 (ALAS-2026-3215)	Nessus	Amazon Linux Local Security Checks	high
304495	SUSE SLED15 / SLES15 Security Update : python-pyasn1 (SUSE-SU-2026:1158-1)	Nessus	SuSE Local Security Checks	high
304433	Ubuntu 14.04 LTS / 16.04 LTS / 18.04 LTS / 20.04 LTS : pyasn1 vulnerabilities (USN-8134-1)	Nessus	Ubuntu Local Security Checks	high
304430	Ubuntu 22.04 LTS / 24.04 LTS / 25.10 : pyasn1 vulnerability (USN-8129-1)	Nessus	Ubuntu Local Security Checks	high
304228	openSUSE 16 Security Update : python-pyasn1 (openSUSE-SU-2026:20418-1)	Nessus	SuSE Local Security Checks	high
303959	SUSE SLED15 / SLES15 / openSUSE 15 Security Update : python-pyasn1 (SUSE-SU-2026:1075-1)	Nessus	SuSE Local Security Checks	high
303951	SUSE SLES12 Security Update : python-pyasn1 (SUSE-SU-2026:1076-1)	Nessus	SuSE Local Security Checks	high
302886	Linux Distros Unpatched Vulnerability : CVE-2026-30922	Nessus	Misc.	high

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