A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.
View on MITREWhen a security mechanism can be forced to downgrade to use a less secure algorithm, this can make it easier for attackers to compromise the product by exploiting weaker algorithm. The victim might not be aware that the less secure algorithm is being used. For example, if an attacker can force a communications channel to use cleartext instead of strongly-encrypted data, then the attacker could read the channel by sniffing, instead of going through extra effort of trying to decrypt the data using brute force techniques.
No mitigation information available for this CWE.
No detection method information available for this CWE.
Attacker can select an older version of the software to exploit its vulnerabilities.
View DetailsImproper prioritization of encryption ciphers during negotiation leads to use of a weaker cipher.
View Detailschain: SSL/TLS implementation disables a verification step (CWE-325) that enables a downgrade attack to a weaker protocol.
View DetailsTelnet protocol implementation allows downgrade to weaker authentication and encryption using an Adversary-in-the-Middle AITM attack.
View DetailsSSH server implementation allows override of configuration setting to use weaker authentication schemes. This may be a composite with CWE-642.
View DetailsNo relationship information available for this CWE.
CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade') is a Common Weakness Enumeration (CWE) entry maintained by MITRE. A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties. When a security mechanism can be forced to downgrade to use a less secure algorithm, this can make it easier for attackers to compromise the product by exploiting weaker algorithm. The victim might not be aware that the less secure algorithm is being used. For example, if an attacker can force a communications channel to use cleartext instead of strongly-encrypted data, then the attacker could read the channel by sniffing, instead of going through extra effort of trying to decrypt the data using brute force techniques.
If exploited, CWE-757 (Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')) it can compromise Access Control, leading to outcomes such as Bypass Protection Mechanism.
MITRE documents real CVEs mapped to CWE-757, including CVE-2006-4302, CVE-2006-4407, CVE-2005-2969, CVE-2001-1444 and CVE-2002-1646. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.
A CWE (Common Weakness Enumeration) like CWE-757 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.