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

  - The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes     it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of     ciphertext in a large number of sessions that use the same plaintext. (CVE-2013-2566)

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

At least one of the SSL or TLS services on the remote host supports the use of RC4 for encryption.

RC4 does not meet the PCI definition of strong cryptography as defined by NIST Special Publication 800-57 Part 1.

The RC4 cipher is flawed in its generation of a pseudo-random stream of bytes so that a wide variety of small biases are introduced into the stream, decreasing its randomness. If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an attacker is able to obtain many (i.e., tens of millions) ciphertexts, the attacker may be able to derive the plaintext.

Multiple security issues was identified and fixed in mozilla NSPR and NSS :

Mozilla Network Security Services (NSS) before 3.15.2 does not ensure that data structures are initialized before read operations, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors that trigger a decryption failure (CVE-2013-1739).

Integer overflow in Mozilla Network Security Services (NSS) 3.15 before 3.15.3 allows remote attackers to cause a denial of service or possibly have unspecified other impact via a large size value (CVE-2013-1741).

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of ciphertext in a large number of sessions that use the same plaintext (CVE-2013-2566).

Mozilla Network Security Services (NSS) 3.14 before 3.14.5 and 3.15 before 3.15.3 allows remote attackers to cause a denial of service or possibly have unspecified other impact via invalid handshake packets (CVE-2013-5605).

The CERT_VerifyCert function in lib/certhigh/certvfy.c in Mozilla Network Security Services (NSS) 3.15 before 3.15.3 provides an unexpected return value for an incompatible key-usage certificate when the CERTVerifyLog argument is valid, which might allow remote attackers to bypass intended access restrictions via a crafted certificate (CVE-2013-5606).

Integer overflow in the PL_ArenaAllocate function in Mozilla Netscape Portable Runtime (NSPR) before 4.10.2, as used in Firefox before 25.0.1, Firefox ESR 17.x before 17.0.11 and 24.x before 24.1.1, and SeaMonkey before 2.22.1, allows remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a crafted X.509 certificate, a related issue to CVE-2013-1741 (CVE-2013-5607).

The NSPR packages has been upgraded to the 4.10.2 version and the NSS packages has been upgraded to the 3.15.3 version which is unaffected by these security flaws.

Additionally the rootcerts packages has been upgraded with the latest certdata.txt file as of 2013/11/11 from mozilla.

Multiple security issues were discovered in Thunderbird. If a user were tricked into connecting to a malicious server, an attacker could possibly exploit these to cause a denial of service via application crash, potentially execute arbitrary code, or lead to information disclosure. (CVE-2013-1741, CVE-2013-2566, CVE-2013-5605, CVE-2013-5607).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host supports the use of RC4 in one or more cipher suites.
The RC4 cipher is flawed in its generation of a pseudo-random stream of bytes so that a wide variety of small biases are introduced into the stream, decreasing its randomness.

If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an attacker is able to obtain many (i.e., tens of millions) ciphertexts, the attacker may be able to derive the plaintext.

The remote host is affected by the vulnerability described in GLSA-201406-19 (Mozilla Network Security Service: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in the Mozilla Network       Security Service. Please review the CVE identifiers referenced below for       more details about the vulnerabilities.
  Impact :

    A remote attacker can cause a Denial of Service condition.
  Workaround :

    There is no known workaround at this time.

Multiple security issues were discovered in Firefox. If a user were tricked into opening a specially crafted page, an attacker could possibly exploit these to cause a denial of service via application crash, potentially execute arbitrary code, or lead to information disclosure. (CVE-2013-1741, CVE-2013-2566, CVE-2013-5605, CVE-2013-5607).

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases, which makes it easier for remote attackers to conduct plaintext-recovery attacks via statistical analysis of ciphertext in a large number of sessions that use the same plaintext.
(CVE-2013-2566)

Impact

Remote attackers may be able to conduct plaintext-recovery attacks using statistical analysis of ciphertext.

The remote host is affected by the vulnerability described in GLSA-201504-01 (Mozilla Products: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Firefox, Thunderbird,       and SeaMonkey. Please review the CVE identifiers referenced below for       details.
  Impact :

    A remote attacker could entice a user to view a specially crafted web       page or email, possibly resulting in execution of arbitrary code or a       Denial of Service condition. Furthermore, a remote attacker may be able       to perform Man-in-the-Middle attacks, obtain sensitive information, spoof       the address bar, conduct clickjacking attacks, bypass security       restrictions and protection mechanisms,  or have other unspecified       impact.
  Workaround :

    There are no known workarounds at this time.

The remote host supports the use of RC4 in one or more cipher suites. The RC4 cipher is flawed in its generation of a pseudo-random stream of bytes so that a wide variety of small biases are introduced into the stream, decreasing its randomness. If plaintext is repeatedly encrypted (e.g., HTTP cookies), and an attacker is able to obtain many (i.e., tens of millions) ciphertexts, the attacker may be able to derive the plaintext.

Prior to UR firmware Version 8.1x, UR supported various encryption and MAC algorithms for SSH communication, some of which are weak.

This plugin only works with Tenable.ot.
Please visit https://www.tenable.com/products/tenable-ot for more information.

ID	Name	Product	Family	Published	Updated	Severity
217995	Linux Distros Unpatched Vulnerability : CVE-2013-2566	Nessus	Misc.	3/4/2025	9/3/2025	medium
106458	SSL/TLS Services Support RC4 (PCI DSS)	Nessus	General	1/29/2018	10/31/2025	medium
70998	Mandriva Linux Security Advisory : nss (MDVSA-2013:270)	Nessus	Mandriva Local Security Checks	11/21/2013	1/6/2021	high
71036	Ubuntu 12.04 LTS / 12.10 / 13.04 / 13.10 : thunderbird vulnerabilities (USN-2032-1)	Nessus	Ubuntu Local Security Checks	11/22/2013	9/19/2019	medium
65821	SSL RC4 Cipher Suites Supported (Bar Mitzvah)	Nessus	General	4/5/2013	5/9/2025	medium
76178	GLSA-201406-19 : Mozilla Network Security Service: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	6/23/2014	1/6/2021	medium
71021	Ubuntu 12.04 LTS / 12.10 / 13.04 / 13.10 : firefox vulnerabilities (USN-2031-1)	Nessus	Ubuntu Local Security Checks	11/21/2013	9/19/2019	medium
78155	F5 Networks BIG-IP : TLS/SSL RC4 vulnerability (K14638)	Nessus	F5 Networks Local Security Checks	10/10/2014	3/10/2021	medium
82632	GLSA-201504-01 : Mozilla Products: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	4/8/2015	1/11/2021	critical
7282	SSL RC4 Cipher Suites Supported (Bar Mitzvah)	Nessus Network Monitor	Generic	8/29/2017	8/16/2018	medium
503343	GE Multilin UR Family Inadequate Encryption Strength (CVE-2013-2566)	Tenable OT Security	Tenable.ot	9/29/2025	9/29/2025	high

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