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CVE-2013-2566

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases,...

5.9 Medium

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
None
Availability
None

Exploit likelihood

84.4%Up 80.1 points since Feb 4, 2022
90%50%10%1%

What each source reports

CVE List 5.9

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.

Record
CVE-2013-2566
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-327
Updated
2026-11-02
EUVDEUVD-2013-2508 5.9

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.

Record
EUVD-2013-2508
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-f67x-vqh9-8p43 5.9

The RC4 algorithm, as used in the TLS protocol and SSL protocol, has many single-byte biases,...

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.

Record
GHSA-f67x-vqh9-8p43
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness
CWE-326
Updated
2026-11-02
NVD 5.9

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.

Record
CVE-2013-2566
CVSS 3.1
5.9 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS 3.0
5.9 MediumCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:P/I:N/A:N
Weakness
CWE-326, CWE-327
Updated
2026-11-02
OSVMGASA-2013-0337 No score

Updated firefox, rootcerts, nspr & nss packages fix security vulnerabilities

Updated nspr and nss packages fix security vulnerabilities:

Potentially exploitable buffer overflow in NSS before 3.15.3 that 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 NSS 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).

Runaway memset due to an integer truncation in certificate parsing on 64-bit computers in NSS before 3.15.3 leading to a crash by attempting to write 4Gb of nulls (CVE-2013-1741).

Integer overflow in NSPR before 4.10.2 due to unsigned integer wrapping in PL_ArenaAllocate (CVE-2013-5607).

NSS lowered the priority of RC4 in cipher suite advertisement so that more secure ciphers instead of RC4 are likely to be chosen by the server, because of plaintext recovery attacks possible with RC4 (CVE-2013-2566).

This also updates to the latest root certificate data from Mozilla.

Additionally, The latest Firefox ESR version, which fixes an issue with translated strings not being used in some cases, is also being provided.

Record
MGASA-2013-0337
Updated
2026-11-02

Affected products

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Affected packages

Affected packages
PackageAffectedFixed
rootcerts
Mageia:2
From an advisory covering 5 CVEs
before 20131111.00-1.mga2
20131111.00-1.mga2
nspr
Mageia:2
From an advisory covering 5 CVEs
before 4.10.2-1.mga2
4.10.2-1.mga2
nss
Mageia:2
From an advisory covering 5 CVEs
before 3.15.3-1.mga2
3.15.3-1.mga2
firefox
Mageia:2
From an advisory covering 5 CVEs
before 24.1.1-1.mga2
24.1.1-1.mga2
firefox-l10n
Mageia:2
From an advisory covering 5 CVEs
before 24.1.1-1.mga2
24.1.1-1.mga2
rootcerts
Mageia:3
From an advisory covering 5 CVEs
before 20131111.00-1.mga3
20131111.00-1.mga3
nspr
Mageia:3
From an advisory covering 5 CVEs
before 4.10.2-1.mga3
4.10.2-1.mga3
nss
Mageia:3
From an advisory covering 5 CVEs
before 3.15.3-1.mga3
3.15.3-1.mga3
firefox
Mageia:3
From an advisory covering 5 CVEs
before 24.1.1-1.mga3
24.1.1-1.mga3
firefox-l10n
Mageia:3
From an advisory covering 5 CVEs
before 24.1.1-1.mga3
24.1.1-1.mga3

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
MetasploitSSL/TLS Version Detection2014-10-14

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, Metasploit, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2013-2566 is a medium vulnerability (CVSS 5.9) in Canonical Ubuntu Linux, published March 14, 2013. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 84.4%, the 99th percentile. No source names a fixed version.

References

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