Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated request body containing millions of separator-delimited fields can synchronously stall the single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to 104857600 bytes. This issue is fixed in version 6.5.8.

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

  - Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses
    application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without
    passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch
    through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an
    unauthenticated request body containing millions of separator-delimited fields can synchronously stall the
    single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which
    defaults to 104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-3092 advisory.

    Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses     application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without     passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch     through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an     unauthenticated request body containing millions of separator-delimited fields can synchronously stall the     single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which     defaults to 104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

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 version of python3-tornado installed on the remote host is prior to 5.0.2-4. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3924 advisory.

    Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses     application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without     passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch     through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an     unauthenticated request body containing millions of separator-delimited fields can synchronously stall the     single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which     defaults to 104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

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 version of python-tornado installed on the remote host is prior to 4.2.1-3. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3925 advisory.

    Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses     application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without     passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch     through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an     unauthenticated request body containing millions of separator-delimited fields can synchronously stall the     single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which     defaults to 104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

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-2026:4073-1 advisory.

    This update for python-tornado fixes the following issue:

    - CVE-2026-82397: an unauthenticated request body containing millions of separator-delimited fields can     synchronously       stall the single-threaded event loop and delay every connection (bsc#1277725).

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 host has a package installed that is affected by a vulnerability as referenced in the SUSE-SU-2026:4076-1 advisory.

    This update for python-tornado6 fixes the following issue

    - CVE-2026-82397: an unauthenticated request body containing millions of separator-delimited fields can     synchronously       stall the single-threaded event loop and delay every connection (bsc#1277725).

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 AlmaLinux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:67147 advisory.

    * tornado: Tornado: Information disclosure via improper handling of credentials during HTTP redirects     (CVE-2026-49853)
      * tornado: Tornado: Denial of Service via uncontrolled gzip decompression memory consumption     (CVE-2026-49855)

Tenable has extracted the preceding description block directly from the AlmaLinux 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 version of the Tornado Python package installed on the remote host is prior to 6.5.8. It is, therefore, affected by a denial of service vulnerability:

  - Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses     application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without     passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch     through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an unauthenticated     request body containing millions of separator-delimited fields can synchronously stall the single-threaded     event loop and delay every connection. The body is bounded only by max_buffer_size, which defaults to     104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

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.

  - Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.8, Tornado parses     application/x-www-form-urlencoded request bodies with urllib.parse.parse_qs in tornado/escape.py without     passing max_num_fields. RequestHandler._execute in tornado/web.py parses the body before handler dispatch     through HTTPServerRequest._parse_body and parse_body_arguments in tornado/httputil.py, so an     unauthenticated request body containing millions of separator-delimited fields can synchronously stall the     single-threaded event loop and delay every connection. The body is bounded only by max_buffer_size, which     defaults to 104857600 bytes. This issue is fixed in version 6.5.8. (CVE-2026-82397)

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

ID	Name	Product	Family	Type	Severity
455299	Echo: tornado: security update to 6.5.8	Tenable Cloud Security	Echo Local Security Checks	Local	high
455299	Echo: tornado: security update to 6.5.8	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
351062	Amazon Linux 2023 : python3.13-tornado (ALAS2023-2026-3092)	Nessus	Amazon Linux Local Security Checks	Local	high
351043	Amazon Linux 2 : python3-tornado (ALAS-2026-3924)	Nessus	Amazon Linux Local Security Checks	Local	high
351036	Amazon Linux 2 : python-tornado (ALAS-2026-3925)	Nessus	Amazon Linux Local Security Checks	Local	high
348407	SUSE SLED15 / SLES15 Security Update : python-tornado (SUSE-SU-2026:4073-1)	Nessus	SuSE Local Security Checks	Local	high
348404	SUSE SLED15 / SLES15 Security Update : python-tornado6 (SUSE-SU-2026:4076-1)	Nessus	SuSE Local Security Checks	Local	high
345943	AlmaLinux 10 : python-tornado (ALSA-2026:67147)	Nessus	Alma Linux Local Security Checks	Local	high
344487	Python Library Tornado < 6.5.8 DoS (CVE-2026-82397)	Nessus	Misc.	Local	high
342168	Linux Distros Unpatched Vulnerability : CVE-2026-82397	Nessus	Misc.	Local	high

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CVE-2026-82397

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