Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form, which the HTTP specification prohibits because any transfer coding must be wrapped within chunked encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1 is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients' future requests. This issue is fixed in version 7.6.

The AlmaLinux 9.6 host has a package installed that is affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1793281224 advisory.

  - Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of     behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-     Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form,     which the HTTP specification prohibits because any transfer coding must be wrapped within chunked     encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1     is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an     HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker     to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients'     future requests. This issue is fixed in version 7.6. (CVE-2026-61642)

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

The Rocky Linux 9.6 host has a package installed that is affected by a vulnerability as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1793281224 advisory.

  - Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of     behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-     Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form,     which the HTTP specification prohibits because any transfer coding must be wrapped within chunked     encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1     is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an     HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker     to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients'     future requests. This issue is fixed in version 7.6. (CVE-2026-61642)

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 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-8941-1 advisory.

    It was discovered that Squid incorrectly handled certain HTTP Transfer- Encoding headers. An attacker     could possibly use this issue to perform HTTP request smuggling attacks, bypass security mechanisms, or     poison web caches.

    (CVE-2026-61642)

    It was discovered that Squid incorrectly handled certain cache digest replies, which could lead to a     buffer overflow. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a     denial of service. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS.
    (CVE-2026-50012)

    It was discovered that Squid incorrectly handled parsing certain FTP directory listings. A remote attacker     could possibly use this issue to obtain sensitive information. This issue only affected Ubuntu 16.04 LTS,     Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-47729)

    It was discovered that Squid incorrectly handled certain ICP traffic. A remote attacker could possibly use     this issue to cause Squid to crash, resulting in a denial of service. This issue only affected Ubuntu     16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2026-32748, CVE-2026-33526)

    It was discovered that Squid incorrectly handled certain ICP requests. A remote attacker could possibly     use this issue to obtain sensitive information. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04     LTS, and Ubuntu 20.04 LTS. (CVE-2026-33515)

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 AlmaLinux 9.2 host has a package installed that is affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.2:CLSA-2026:1792517219 advisory.

  - Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of     behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-     Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form,     which the HTTP specification prohibits because any transfer coding must be wrapped within chunked     encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1     is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an     HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker     to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients'     future requests. This issue is fixed in version 7.6. (CVE-2026-61642)

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 squid installed on the remote host is prior to 3.5.20-17. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3961 advisory.

    Due to a CWE-841 Improper Enforcement of Behavioral Workflowbug Squid is vulnerable to a Request Smuggling     attack againstHTTP/1.1 Transfer-Encoding.

    This problem allows a trusted client to perform an HTTP RequestSmuggling attack when HTTP/1.1 is used.
    Bypassing securitymechanisms that may be in place between attacker and Squid.

    When there is an HTTP cache operating prior to the affectedSquid, this Request Smuggling attack also     allows the attackerto poison that web cache and store arbitrary malicious contentat any URL for delivery     to other clients future requests. (CVE-2026-61642)

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.

It is, therefore, affected by a vulnerability as referenced in the ALAS2023-2026-3145 advisory.

    Due to a CWE-841 Improper Enforcement of Behavioral Workflowbug Squid is vulnerable to a Request Smuggling     attack againstHTTP/1.1 Transfer-Encoding.

    This problem allows a trusted client to perform an HTTP RequestSmuggling attack when HTTP/1.1 is used.
    Bypassing securitymechanisms that may be in place between attacker and Squid.

    When there is an HTTP cache operating prior to the affectedSquid, this Request Smuggling attack also     allows the attackerto poison that web cache and store arbitrary malicious contentat any URL for delivery     to other clients future requests. (CVE-2026-61642)

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

  - Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of     behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-     Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form,     which the HTTP specification prohibits because any transfer coding must be wrapped within chunked     encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1     is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an     HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker     to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients'     future requests. This issue is fixed in version 7.6. (CVE-2026-61642)

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

ID	Name	Product	Family	Type	Severity
373741	AlmaLinux 9.6 [TuxCare] Security Update: squid (ALMALINUX9.6:CLSA-2026:1793281224)	Nessus	Alma Linux Local Security Checks	Local	high
373733	Rocky Linux 9.6 [TuxCare] Security Update: squid (ALMALINUX9.6:CLSA-2026:1793281224)	Nessus	Rocky Linux Local Security Checks	Local	high
369509	Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS / 22.04 LTS / 24.04 LTS : Squid vulnerabilities (USN-8941-1)	Nessus	Ubuntu Local Security Checks	Local	critical
367919	AlmaLinux 9.2 [TuxCare] Security Update: squid Multiple Vulnerabilities (ALMALINUX9.2:CLSA-2026:1792517219)	Nessus	Alma Linux Local Security Checks	Local	critical
351081	Amazon Linux 2 : squid (ALAS-2026-3961)	Nessus	Amazon Linux Local Security Checks	Local	high
351026	Amazon Linux 2023 : squid (ALAS2023-2026-3145)	Nessus	Amazon Linux Local Security Checks	Local	high
346826	Linux Distros Unpatched Vulnerability : CVE-2026-61642	Nessus	Misc.	Local	high

Detections

Analytics

CVE-2026-61642

high

Tenable Plugins

high

high

critical

critical

high

high

high