CWE-757: Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade')
low-riskA 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.
Common Consequences
Detection Methods
Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Real-World Examples (10)
| CVE | CVSS | EPSS | KEV |
|---|---|---|---|
| CVE-2020-10135 | 5.4 | 20.2% | — |
| CVE-2024-20069 | 6.5 | 1.0% | — |
| CVE-2017-9267 | 6.5 | 0.7% | — |
| CVE-2023-2974 | 6.5 | 0.5% | — |
| CVE-2017-9269 | 7.7 | 0.5% | — |
| CVE-2021-36326 | 6.5 | 0.4% | — |
| CVE-2025-24154 | 9.1 | 0.3% | — |
| CVE-2019-16791 | 6.9 | 0.3% | — |
| CVE-2024-23656 | 7.5 | 0.2% | — |
| CVE-2019-14887 | 9.1 | 0.2% | — |