phpseclib is a PHP secure communications library. Starting in 0.1.1 and prior to 3.0.51, 2.0.53, and 1.0.28, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != operator to compare a received SSH packet HMAC against the locally computed HMAC. != on equal-length binary strings in PHP uses memcmp(), which short-circuits on the first differing byte. This is a real variable-time comparison (CWE-208), proven by scaling benchmarks. This vulnerability is fixed in 3.0.51, 2.0.53, and 1.0.28.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the 9647af6d-7a05-11f1-99fc-40b034429ecf advisory.

    Cacti project reports:
    This release includes fixes for a number of vulnerabilities that were responsibly disclosed by external     researchers

Tenable has extracted the preceding description block directly from the FreeBSD 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 Debian 11 host has a package installed that is affected by multiple vulnerabilities as referenced in the dla-4670 advisory.

    - -----------------------------------------------------------------------     Debian LTS Advisory DLA-4670-1              debian-lts@lists.debian.org     https://www.debian.org/lts/security/                      Utkarsh Gupta     July 05, 2026                               https://wiki.debian.org/LTS
    - -----------------------------------------------------------------------

    Package        : php-phpseclib     Version        : 2.0.30-2+deb11u3     CVE ID         : CVE-2023-52892 CVE-2026-32935 CVE-2026-40194                      CVE-2026-44167 CVE-2026-55599     Debian Bug     : 1131483

    Several vulnerabilities were discovered in phpseclib, a PHP secure     communications library, which could result in hostname validation     bypass, timing side-channel attacks, denial of service, and     server-side request forgery (SSRF).

    CVE-2023-52892

        X509.php did not properly escape regular expression special         characters in a certificate's subjectAltName, allowing a crafted         certificate to bypass hostname validation in validateURL().

    CVE-2026-32935

        The block cipher unpadding routine in Crypt/Base.php used a         short-circuiting comparison, creating a timing side channel that         could aid padding-oracle-style attacks.

    CVE-2026-40194

        The SSH2 implementation compared incoming packet HMACs using a         variable-time string comparison, creating a timing side channel         on cryptographic material.

    CVE-2026-44167

        The ASN.1 decoder's 4096-byte Object Identifier limit (mitigating         CVE-2024-27355) was still large enough to allow an OID         amplification denial of service via crafted ASN.1 structures.

    CVE-2026-55599

        File_X509 could automatically fetch a URL from a certificate's         Authority Information Access extension without validating the         destination, allowing SSRF via a crafted certificate.

    For Debian 11 bullseye, these problems have been fixed in version     2.0.30-2+deb11u3.

    We recommend that you upgrade your php-phpseclib packages.

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

    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 remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-6599e30e04 advisory.

    33.0.3 Release

Tenable has extracted the preceding description block directly from the Fedora 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 Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-cb5661d883 advisory.

    33.0.3 Release

Tenable has extracted the preceding description block directly from the Fedora 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 Fedora 42 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-2fed8dd674 advisory.

    33.0.3 Release

Tenable has extracted the preceding description block directly from the Fedora 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:

  - phpseclib is a PHP secure communications library. Starting in 0.1.1 and prior to 3.0.51, 2.0.53, and
    1.0.28, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != operator to compare a received SSH packet
    HMAC against the locally computed HMAC. != on equal-length binary strings in PHP uses memcmp(), which
    short-circuits on the first differing byte. This is a real variable-time comparison (CWE-208), proven by
    scaling benchmarks. This vulnerability is fixed in 3.0.51, 2.0.53, and 1.0.28. (CVE-2026-40194)

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

  - phpseclib is a PHP secure communications library. Starting in 0.1.1 and prior to 3.0.51, 2.0.53, and     1.0.28, phpseclib\Net\SSH2::get_binary_packet() uses PHP's != operator to compare a received SSH packet     HMAC against the locally computed HMAC. != on equal-length binary strings in PHP uses memcmp(), which     short-circuits on the first differing byte. This is a real variable-time comparison (CWE-208), proven by     scaling benchmarks. This vulnerability is fixed in 3.0.51, 2.0.53, and 1.0.28. (CVE-2026-40194)

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

ID	Name	Product	Family	Severity
325775	FreeBSD : cacti -- multiple vulnerabilities (9647af6d-7a05-11f1-99fc-40b034429ecf)	Nessus	FreeBSD Local Security Checks	critical
325133	Debian dla-4670 : php-phpseclib - security update	Nessus	Debian Local Security Checks	high
313733	Fedora 43 : nextcloud (2026-6599e30e04)	Nessus	Fedora Local Security Checks	medium
313662	Fedora 44 : nextcloud (2026-cb5661d883)	Nessus	Fedora Local Security Checks	medium
313661	Fedora 42 : nextcloud (2026-2fed8dd674)	Nessus	Fedora Local Security Checks	medium
441563	SCA: security update for phpseclib/phpseclib (GHSA-r854-jrxh-36qx)	Tenable Cloud Security	SCA Checks	low
441563	SCA: security update for phpseclib/phpseclib (GHSA-r854-jrxh-36qx)	Tenable Self-Hosted Container Security	SCA Checks	low
306030	Linux Distros Unpatched Vulnerability : CVE-2026-40194	Nessus	Misc.	low

Detections

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CVE-2026-40194

low

Tenable Plugins

critical

high

medium

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medium

low

low

low