Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This issue is fixed in versions 7.2.1 and 8.0.2.

The remote Debian 12 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4826 advisory.

    - -------------------------------------------------------------------------     Debian LTS Advisory DLA-4826-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                          Abhijith PA     October 07, 2026                              https://wiki.debian.org/LTS
    - -------------------------------------------------------------------------

    Package        : puma     Version        : 5.6.5-3+deb12u2     CVE ID         : CVE-2026-47736 CVE-2026-47737

    Two vulnerabilities were discovered in Puma, a simple, fast, threaded,     and highly concurrent server for Ruby/Rack applications

    CVE-2026-47736

        when PROXY protocol v1 support is enabled, Puma reads incoming         bytes into an internal buffer while waiting for CRLF to determine         whether a PROXY v1 line is present, allowing an attacker that         continuously sends bytes without CRLF to cause unbounded         in-process memory growth and additional CPU cost from repeatedly         scanning the growing buffer.

    CVE-2026-47737

        Puma is vulnerable to source IP spoofing when set_remote_address         proxy_protocol: :v1 is enabled and persistent connections are used         because Puma incorrectly re-parses PROXY protocol headers after         each keep-alive request on the same connection, allowing an         attacker to inject a second PROXY header and overwrite         REMOTE_ADDR.

    For Debian 12 bookworm, these problems have been fixed in version     5.6.5-3+deb12u2.

    We recommend that you upgrade your puma packages.

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

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

Tenable has extracted the preceding description block directly from the Debian 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 Tencent Linux installed on the remote TencentOS Server 4 host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the TSSA-2026:0801 advisory.

    Package updates are available for TencentOS Server 4 that fix the following vulnerabilities:

    CVE-2026-47737:
    Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable     to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections     are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the     same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This     issue is fixed in versions 7.2.1 and 8.0.2.

    CVE-2026-47736:
    Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, when PROXY     protocol v1 support is enabled, Puma reads incoming bytes into an internal buffer while waiting for CRLF     to determine whether a PROXY v1 line is present, allowing an attacker that continuously sends bytes     without CRLF to cause unbounded in-process memory growth and additional CPU cost from repeatedly scanning     the growing buffer. This issue is fixed in versions 7.2.1 and 8.0.2.

Tenable has extracted the preceding description block directly from the Tencent 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 Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Puma is a Ruby/Rack web server built for parallelism. From 5.5.0 until 7.2.1 and 8.0.2, Puma is vulnerable     to source IP spoofing when set_remote_address proxy_protocol: :v1 is enabled and persistent connections     are used because Puma incorrectly re-parses PROXY protocol headers after each keep-alive request on the     same connection, allowing an attacker to inject a second PROXY header and overwrite REMOTE_ADDR. This     issue is fixed in versions 7.2.1 and 8.0.2. (CVE-2026-47737)

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

ID	Name	Product	Family	Type	Severity
363861	Debian dla-4826 : puma - security update	Nessus	Debian Local Security Checks	Local	high
334830	TencentOS Server 4: pcs (TSSA-2026:0801)	Nessus	Tencent Local Security Checks	Local	high
327146	Linux Distros Unpatched Vulnerability : CVE-2026-47737	Nessus	Misc.	Local	high

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