urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so later connections reusing the same context may connect to the HTTPS proxy without certificate verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.

oracle_linux ELSA-2026-85930: ELSA-2026-85930:  python-urllib3 security update (IMPORTANT)

oracle_linux ELSA-2026-85929: ELSA-2026-85929:  python3.12-urllib3 security update (IMPORTANT)

ciq crlsa-2026_84578: CRLSA-2026_84578: Important: python3.14-urllib3 security update

ciq crlsa-2026_84577: CRLSA-2026_84577: Important: python3.14-urllib3 security update

The remote Redhat Enterprise Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:85929 advisory.

    Python is an interpreted, interactive, object-oriented programming language, which includes modules,     classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to     many system calls and libraries, as well as to various windowing systems.

    Security Fix(es):

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)

    * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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 RockyLinux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RLSA-2026:84577 advisory.

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)

    * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

Tenable has extracted the preceding description block directly from the RockyLinux 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 RockyLinux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the RLSA-2026:84578 advisory.

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)

    * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

Tenable has extracted the preceding description block directly from the RockyLinux 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 MiracleLinux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the AXSA:2026-2098:02 advisory.

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)
      * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

Tenable has extracted the preceding description block directly from the MiracleLinux 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 AlmaLinux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:84577 advisory.

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)
      * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

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 remote Oracle Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2026-84577 advisory.

    - CVE-2026-97689 python3.14-urllib3: urllib3: Denial of Service via       unbounded memory allocation in chunk parser

Tenable has extracted the preceding description block directly from the Oracle Linux 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 Oracle Linux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2026-84578 advisory.

    - CVE-2026-97689 python3.14-urllib3: urllib3: Denial of Service via       unbounded memory allocation in chunk parser

Tenable has extracted the preceding description block directly from the Oracle Linux 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 AlmaLinux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:84578 advisory.

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)
      * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

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 remote Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8926-1 advisory.

    Yu-Fu Fu, Seth Larson and Yonatan Magier discovered that urllib3 did not correctly handle certain     certificate validations. An attacker could possibly use this issue to observe or modify forwarded traffic.
    This issue only affected Ubuntu 26.04 LTS. (CVE-2026-97687)

    Martin Desrumaux discovered that urllib3 did not correctly handle decoding certain deflate responses. An     attacker could possibly use this issue to cause a denial of service. This issue only affected Ubuntu 26.04     LTS. (CVE-2026-97688)

    It was discovered that urllib3 did not correctly handle certain memory operations. An attacker could     possibly use this issue to cause a denial of service. (CVE-2026-97689)

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 Redhat Enterprise Linux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:84577 advisory.

    Python is an interpreted, interactive, object-oriented programming language, which includes modules,     classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to     many system calls and libraries, as well as to various windowing systems.

    Security Fix(es):

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)

    * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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 Redhat Enterprise Linux 10 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:84578 advisory.

    Python is an interpreted, interactive, object-oriented programming language, which includes modules,     classes, exceptions, very high level dynamic data types and dynamic typing. Python supports interfaces to     many system calls and libraries, as well as to various windowing systems.

    Security Fix(es):

    * urllib3: urllib3: Denial of Service via unbounded memory allocation in chunk parser (CVE-2026-97689)

    * urllib3: urllib3: Traffic interception via HTTPS proxy TLS configuration override (CVE-2026-97687)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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-2026:4704-1 advisory.

    - CVE-2026-97687: traffic interception due to possible HTTPS proxy TLS configuration override     (bsc#1283908).
    - CVE-2026-97688: denial of service due to infinite loop during chunked Deflate decoding (bsc#1283909).
    - CVE-2026-97689: denial of service due to unbounded memory allocation in chunk parser (bsc#1283910).

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:

  - urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context,
    proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode,
    use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-
    server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an
    application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from
    the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying
    cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so
    later connections reusing the same context may connect to the HTTPS proxy without certificate
    verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after
    the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe
    or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still
    preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.
    (CVE-2026-97687)

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

  - urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context,     proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode,     use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-     server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an     application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from     the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying     cert_reqs=CERT_NONE can overwrite proxy_ssl_context.verify_mode in place, and the mutation persists so     later connections reusing the same context may connect to the HTTPS proxy without certificate     verification. The attack mechanism is that an attacker intercepts and impersonates the HTTPS proxy after     the effective proxy policy accepts the attacker's certificate. The impact is that the attacker can observe     or modify forwarded traffic or receive a target TLS client certificate, while CONNECT tunneling still     preserves the separate end-to-end target TLS connection. This issue is fixed in version 2.8.0.
    (CVE-2026-97687)

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

ID	Name	Product	Family	Type	Severity
367818	RHEL 9 : python3.12-urllib3 (RHSA-2026:85929)	Nessus	Red Hat Local Security Checks	Local	high
367815	RockyLinux 9 : python3.14-urllib3 (RLSA-2026:84577)	Nessus	Rocky Linux Local Security Checks	Local	high
367808	RockyLinux 10 : python3.14-urllib3 (RLSA-2026:84578)	Nessus	Rocky Linux Local Security Checks	Local	high
367719	MiracleLinux 9 : python3.14-urllib3-2.6.3-2.el9_8.6 (AXSA:2026-2098:02)	Nessus	Miracle Linux Local Security Checks	Local	high
367388	AlmaLinux 9 : python3.14-urllib3 (ALSA-2026:84577)	Nessus	Alma Linux Local Security Checks	Local	high
367317	Oracle Linux 9 : python3.14-urllib3 (ELSA-2026-84577)	Nessus	Oracle Linux Local Security Checks	Local	high
367312	Oracle Linux 10 : python3.14-urllib3 (ELSA-2026-84578)	Nessus	Oracle Linux Local Security Checks	Local	high
367292	AlmaLinux 10 : python3.14-urllib3 (ALSA-2026:84578)	Nessus	Alma Linux Local Security Checks	Local	high
367208	Ubuntu 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS / 26.04 LTS : urllib3 vulnerabilities (USN-8926-1)	Nessus	Ubuntu Local Security Checks	Local	high
367183	RHEL 9 : python3.14-urllib3 (RHSA-2026:84577)	Nessus	Red Hat Local Security Checks	Local	high
367182	RHEL 10 : python3.14-urllib3 (RHSA-2026:84578)	Nessus	Red Hat Local Security Checks	Local	high
366748	SUSE SLED15 / SLES15 Security Update : python-urllib3 (SUSE-SU-2026:4704-1)	Nessus	SuSE Local Security Checks	Local	high
460553	Echo: python-3.11: security update to 3.11.17+e2python-urllib3: security update to 1:2.3.0-3+deb13u1+e3urllib3: security update to 2.8.0	Tenable Cloud Security	Echo Local Security Checks	Local	high
460553	Echo: python-3.11: security update to 3.11.17+e2python-urllib3: security update to 1:2.3.0-3+deb13u1+e3urllib3: security update to 2.8.0	Tenable Self-Hosted Container Security	Echo Local Security Checks	Local	high
351296	Linux Distros Unpatched Vulnerability : CVE-2026-97687	Nessus	Misc.	Local	high

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