CVE-2013-2566
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.
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
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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 3.0
- 5.9 Medium
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N - CVSS 2.0
- 4.3 Medium
AV: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
- canonical ubuntu linux
- fujitsu m10-1 firmware
- fujitsu m10-4 firmware
- fujitsu m10-4s firmware
- fujitsu sparc enterprise m3000 firmware
- fujitsu sparc enterprise m4000 firmware
- fujitsu sparc enterprise m5000 firmware
- fujitsu sparc enterprise m8000 firmware
- fujitsu sparc enterprise m9000 firmware
- mozilla firefox
- mozilla seamonkey
- mozilla thunderbird
Affected packages
| Package | Affected | Fixed |
|---|---|---|
rootcertsMageia:2 From an advisory covering 5 CVEs |
before 20131111.00-1.mga2 | 20131111.00-1.mga2 |
nsprMageia:2 From an advisory covering 5 CVEs |
before 4.10.2-1.mga2 | 4.10.2-1.mga2 |
nssMageia:2 From an advisory covering 5 CVEs |
before 3.15.3-1.mga2 | 3.15.3-1.mga2 |
firefoxMageia:2 From an advisory covering 5 CVEs |
before 24.1.1-1.mga2 | 24.1.1-1.mga2 |
firefox-l10nMageia:2 From an advisory covering 5 CVEs |
before 24.1.1-1.mga2 | 24.1.1-1.mga2 |
rootcertsMageia:3 From an advisory covering 5 CVEs |
before 20131111.00-1.mga3 | 20131111.00-1.mga3 |
nsprMageia:3 From an advisory covering 5 CVEs |
before 4.10.2-1.mga3 | 4.10.2-1.mga3 |
nssMageia:3 From an advisory covering 5 CVEs |
before 3.15.3-1.mga3 | 3.15.3-1.mga3 |
firefoxMageia:3 From an advisory covering 5 CVEs |
before 24.1.1-1.mga3 | 24.1.1-1.mga3 |
firefox-l10nMageia: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.
| Source | Link | Date |
|---|---|---|
| Metasploit | SSL/TLS Version Detection | 2014-10-14 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE 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
oracle.com/technetwork/security-advisory/cpujan2018-3236628.html
blog.cryptographyengineering.com/2013/03/attack-of-week-rc4-is-kind-of-broken-in.html
securityfocus.com/bid/58796
oracle.com/technetwork/security-advisory/cpujul2016-2881720.html
cr.yp.to/talks/2013.03.12/slides.pdf
marc.info?l=bugtraq&m=143039468003789&w=2
Show 23 moreShow less
oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html
security.gentoo.org/glsa/201504-01
security.gentoo.org/glsa/glsa-201406-19.xml
oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html
ubuntu.com/usn/USN-2031-1
ubuntu.com/usn/USN-2032-1
my.opera.com/securitygroup/blog/2013/03/20/on-the-precariousness-of-rc4
oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html
opera.com/security/advisory/1046
kb.juniper.net/InfoCenter/index?page=content&id=JSA10705
h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05336888
mozilla.org/security/announce/2013/mfsa2013-103.html
isg.rhul.ac.uk/tls
opera.com/docs/changelogs/unified/1215
h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05289935
nvd.nist.gov/vuln/detail/CVE-2013-2566
github.com/advisories/GHSA-f67x-vqh9-8p43
advisories.mageia.org/MGASA-2013-0337.html
groups.google.com/forum
developer.mozilla.org/en-US/docs/NSS/NSS_3.15.3_release_notes
bugzilla.mozilla.org/show_bug.cgi?id=932310
mozilla.org/en-US/firefox/24.1.1/releasenotes
bugs.mageia.org/show_bug.cgi?id=11669