# What is CVE-2007-0956? > CVE-2007-0956 is a critical-severity flaw (CVSS 10.0) in Kerberos 5 from Mit, published on 6 April 2007. 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 30%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2007-0956 ## 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:** Critical (CVSS 10.0 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:** 30% (latest exploit-likelihood forecast) - **Published:** 6 April 2007 - **Record last updated:** 16 June 2026 - **Main product:** Kerberos 5 from Mit - **Affected products:** 3 ## What is CVE-2007-0956? In plain terms It can be attacked from anywhere on the internet without logging in. If it works, the attacker can read data, change data and take it offline. ### The official description The telnet daemon (telnetd) in MIT krb5 before 1.6.1 allows remote attackers to bypass authentication and gain system access via a username beginning with a '-' character, a similar issue to CVE-2007-0882. ### What kind of flaw is it? - CWE-306: Missing Authentication for Critical Function ### How an attack on it works - Where an attacker can be: Anywhere on the internet - How hard it is to pull off: Easy: no special conditions - Login needed first: No login needed - What an attacker gets: Can read data, change data and take it offline Severity vector: `AV:N/AC:L/Au:N/C:C/I:C/A:C` ## Is CVE-2007-0956 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 30%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: 30%, 30%, 30%, 30%, 30%, 30%, 30%. ### Timeline - 6 April 2007: Published - 10 November 2025: Exploit likelihood fell - 16 June 2026: Record last updated ### How Precursor Intelligence ranks it CVE-2007-0956 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-2007-0956? The published record lists 3 products. Versions are as published: "before 1.6.1" means every version up to, but not including, 1.6.1. - [Kerberos 5](https://www.precursorintelligence.com/product/mit/kerberos_5) by [Mit](https://www.precursorintelligence.com/vendors/mit) (Application): before 1.6.1 - [Ubuntu Linux](https://www.precursorintelligence.com/product/canonical/ubuntu_linux) by [Canonical](https://www.precursorintelligence.com/vendors/canonical) (Operating system): 5.10, 6.06, 6.10 - [Debian Linux](https://www.precursorintelligence.com/product/debian/debian_linux) by [Debian](https://www.precursorintelligence.com/vendors/debian) (Operating system): 3.1, 4.0 ## How do I fix CVE-2007-0956? 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 update named in the vendor’s advisory. We’ve put the advisory first in the list. 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 - [web.mit.edu](http://web.mit.edu/kerberos/www/advisories/MITKRB5-SA-2007-001-telnetd.txt) (Vendor advisory) - [lists.suse.com](http://lists.suse.com/archive/suse-security-announce/2007-Apr/0001.html) (Broken link) - [secunia.com](http://secunia.com/advisories/24706) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24735) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24736) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24740) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24750) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24755) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24757) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24785) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24786) (Third-party advisory) - [secunia.com](http://secunia.com/advisories/24817) (Third-party advisory) - [security.gentoo.org](http://security.gentoo.org/glsa/glsa-200704-02.xml) (Third-party advisory) - [sunsolve.sun.com](http://sunsolve.sun.com/search/document.do?assetkey=1-26-102867-1) (Broken link) - [debian.org](http://www.debian.org/security/2007/dsa-1276) (Third-party advisory) - [kb.cert.org](http://www.kb.cert.org/vuls/id/220816) (Third-party advisory, Government resource) - [mandriva.com](http://www.mandriva.com/security/advisories?name=MDKSA-2007:077) (Third-party advisory) - [redhat.com](http://www.redhat.com/support/errata/RHSA-2007-0095.html) (Third-party advisory) - [securityfocus.com](http://www.securityfocus.com/archive/1/464590/100/0/threaded) (Third-party advisory, Vulnerability database) - [securityfocus.com](http://www.securityfocus.com/archive/1/464666/100/0/threaded) (Third-party advisory, Vulnerability database) - [securityfocus.com](http://www.securityfocus.com/archive/1/464814/30/7170/threaded) (Third-party advisory, Vulnerability database) - [securityfocus.com](http://www.securityfocus.com/bid/23281) (Third-party advisory, Vulnerability database) - [securitytracker.com](http://www.securitytracker.com/id?1017848) (Third-party advisory, Vulnerability database) - [ubuntu.com](http://www.ubuntu.com/usn/usn-449-1) (Third-party advisory) - [us-cert.gov](http://www.us-cert.gov/cas/techalerts/TA07-093B.html) (Third-party advisory, Government resource) - [vupen.com](http://www.vupen.com/english/advisories/2007/1218) (Third-party advisory) - [vupen.com](http://www.vupen.com/english/advisories/2007/1249) (Third-party advisory) - [exchange.xforce.ibmcloud.com](https://exchange.xforce.ibmcloud.com/vulnerabilities/33414) (Third-party advisory, Vulnerability database) - [oval.cisecurity.org](https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10046) (Broken link, Third-party advisory) ## Questions ### What is CVE-2007-0956? CVE-2007-0956 is a critical-severity flaw in Kerberos 5 from Mit, published on 6 April 2007. It can be attacked from anywhere on the internet without logging in. If it works, the attacker can read data, change data and take it offline. ### How serious is CVE-2007-0956? It scores 10.0 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2007-0956 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-2007-0956 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 30%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2007-0956 affect? For Kerberos 5 from Mit: before 1.6.1. The record lists 3 products in all, each with its versions, under "Who is affected" on this page. ### How do I fix CVE-2007-0956? Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. ## Does CVE-2007-0956 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. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact