# What is CVE-2013-2566?

> CVE-2013-2566 is a medium-severity flaw (CVSS 5.9) in Communications Application Session Controller from Oracle, published on 15 March 2013. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at 84%. If you run an affected version, plan in the vendor’s fix.

Canonical page: https://www.precursorintelligence.com/what-is/cve-2013-2566

## At a glance

- **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.
- **Precursor Intelligence risk score:** 56 out of 100 (Medium); action: Plan remediation. Kept up to date as the evidence changes.
- **Severity:** Medium (CVSS 5.9 out of 10)
- **Known to be exploited:** No, not on the list of flaws known to be exploited today
- **Chance of use in the next 30 days:** 84% (latest exploit-likelihood forecast)
- **Published:** 15 March 2013
- **Record last updated:** 16 June 2026
- **Main product:** Communications Application Session Controller from Oracle
- **Affected products:** 16

## What is CVE-2013-2566? In plain terms

It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data.

### The official description

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.

### What kind of flaw is it?

- CWE-326: Inadequate Encryption Strength
- CWE-327: Use of a Broken or Risky Cryptographic Algorithm

### How an attack on it works

- Where an attacker can be: Anywhere on the internet
- How hard it is to pull off: Hard: conditions must line up
- Login needed first: No login needed
- Does someone have to click: No, nobody has to do anything
- What an attacker gets: Can read data

Severity vector: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N`

## Is CVE-2013-2566 being exploited? Not that we know of

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 84%. That can change at any time, which is why we keep watching.

Exploit likelihood over the last 7 days: 84%, 84%, 84%, 84%, 84%, 84%, 84%.

### Timeline

- 15 March 2013: Published
- 16 June 2026: Record last updated

### How Precursor Intelligence ranks it

CVE-2013-2566 scores **56 out of 100 (Medium)**, with the action "Plan remediation".

Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less:

- Evidence it is being exploited: biggest factor
- How severe it is: strong factor
- How widely exposed it is: smaller factor
- Threat activity around it: smaller factor

85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it.

## Who is affected by CVE-2013-2566?

The published record lists 16 products. Versions are as published: "before 17.0.11" means every version up to, but not including, 17.0.11.

- [Communications Application Session Controller](https://www.precursorintelligence.com/product/oracle/communications_application_session_controller) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 3.0.0 to 3.9.1
- [HTTP Server](https://www.precursorintelligence.com/product/oracle/http_server) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Application): 11.1.1.7.0, 11.1.1.9.0, 12.1.3.0.0, 12.2.1.1.0, 12.2.1.2.0
- [Ubuntu Linux](https://www.precursorintelligence.com/product/canonical/ubuntu_linux) by [Canonical](https://www.precursorintelligence.com/vendors/canonical) (Operating system): 12.04, 12.10, 13.04, 13.10
- [Firefox](https://www.precursorintelligence.com/product/mozilla/firefox) by [Mozilla](https://www.precursorintelligence.com/vendors/mozilla) (Application): before 17.0.11, before 25.0.1, 24.1.0 to before 24.1.1
- [Integrated Lights Out Manager Firmware](https://www.precursorintelligence.com/product/oracle/integrated_lights_out_manager_firmware) by [Oracle](https://www.precursorintelligence.com/vendors/oracle) (Operating system): 3.0.0 to 3.2.11, 4.0.0 to 4.0.4
- [M10-1 Firmware](https://www.precursorintelligence.com/product/fujitsu/m10-1_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp2280
- [M10-4 Firmware](https://www.precursorintelligence.com/product/fujitsu/m10-4_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp2280
- [M10-4s Firmware](https://www.precursorintelligence.com/product/fujitsu/m10-4s_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp2280
- [Seamonkey](https://www.precursorintelligence.com/product/mozilla/seamonkey) by [Mozilla](https://www.precursorintelligence.com/vendors/mozilla) (Application): before 2.22.1
- [Sparc Enterprise M3000 Firmware](https://www.precursorintelligence.com/product/fujitsu/sparc_enterprise_m3000_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp_1121
- [Sparc Enterprise M4000 Firmware](https://www.precursorintelligence.com/product/fujitsu/sparc_enterprise_m4000_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp_1121
- [Sparc Enterprise M5000 Firmware](https://www.precursorintelligence.com/product/fujitsu/sparc_enterprise_m5000_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp_1121
- [Sparc Enterprise M8000 Firmware](https://www.precursorintelligence.com/product/fujitsu/sparc_enterprise_m8000_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp_1121
- [Sparc Enterprise M9000 Firmware](https://www.precursorintelligence.com/product/fujitsu/sparc_enterprise_m9000_firmware) by [Fujitsu](https://www.precursorintelligence.com/vendors/fujitsu) (Operating system): xcp to before xcp_1121
- [Thunderbird](https://www.precursorintelligence.com/product/mozilla/thunderbird) by [Mozilla](https://www.precursorintelligence.com/vendors/mozilla) (Application): before 24.1.1
- [Thunderbird Esr](https://www.precursorintelligence.com/product/mozilla/thunderbird_esr) by [Mozilla](https://www.precursorintelligence.com/vendors/mozilla) (Application): before 17.0.11

## How do I fix CVE-2013-2566?

1. **Check whether you run it.** Compare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
2. **Apply the vendor’s fix.** Install the latest update from the vendor. The references list where the vendor has published details.
3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood.

### References

- [blog.cryptographyengineering.com](http://blog.cryptographyengineering.com/2013/03/attack-of-week-rc4-is-kind-of-broken-in.html) (Third-party advisory)
- [cr.yp.to](http://cr.yp.to/talks/2013.03.12/slides.pdf) (Third-party advisory)
- [kb.juniper.net](http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705) (Third-party advisory)
- [marc.info](http://marc.info/?l=bugtraq&m=143039468003789&w=2) (Issue tracking, Third-party advisory)
- [my.opera.com](http://my.opera.com/securitygroup/blog/2013/03/20/on-the-precariousness-of-rc4) (Third-party advisory)
- [security.gentoo.org](http://security.gentoo.org/glsa/glsa-201406-19.xml) (Third-party advisory)
- [isg.rhul.ac.uk](http://www.isg.rhul.ac.uk/tls/) (Third-party advisory)
- [mozilla.org](http://www.mozilla.org/security/announce/2013/mfsa2013-103.html) (Third-party advisory)
- [opera.com](http://www.opera.com/docs/changelogs/unified/1215/) (Third-party advisory)
- [opera.com](http://www.opera.com/security/advisory/1046) (Third-party advisory)
- [oracle.com](http://www.oracle.com/technetwork/security-advisory/cpuapr2016v3-2985753.html) (Third-party advisory)
- [oracle.com](http://www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html) (Third-party advisory)
- [oracle.com](http://www.oracle.com/technetwork/security-advisory/cpujul2016-2881720.html) (Third-party advisory)
- [oracle.com](http://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html) (Third-party advisory)
- [oracle.com](http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html) (Third-party advisory)
- [securityfocus.com](http://www.securityfocus.com/bid/58796) (Third-party advisory, Vulnerability database)
- [ubuntu.com](http://www.ubuntu.com/usn/USN-2031-1) (Third-party advisory)
- [ubuntu.com](http://www.ubuntu.com/usn/USN-2032-1) (Third-party advisory)
- [h20566.www2.hpe.com](https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05289935) (Third-party advisory)
- [h20566.www2.hpe.com](https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05336888) (Third-party advisory)
- [security.gentoo.org](https://security.gentoo.org/glsa/201504-01) (Third-party advisory)

## Questions

### What is CVE-2013-2566?

CVE-2013-2566 is a medium-severity flaw in Communications Application Session Controller from Oracle, published on 15 March 2013. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data.

### How serious is CVE-2013-2566?

It scores 5.9 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2013-2566 is 56 out of 100, which is Medium. Its action is "Plan remediation". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month.

### Is CVE-2013-2566 being exploited?

It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at 84%. That can change at any time, which is why we keep watching.

### Which versions does CVE-2013-2566 affect?

For Communications Application Session Controller from Oracle: 3.0.0 to 3.9.1. The record lists 16 products in all, each with its versions, under "Who is affected" on this page.

### How do I fix CVE-2013-2566?

Install the update the vendor names in its advisory. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet.

## Does CVE-2013-2566 affect you?

Precursor Intelligence keeps checking for you:

- **Tell us what you run.** Pick your software from a list, or let us work it out from your website.
- **We match it to every flaw.** Over 400,000 published flaws, checked against your list.
- **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it.
- **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools.

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