-1' OR 5*5=26 --

It looks like an SQL injection payload: -1' OR 5*5=26 --

What it is doing (in brief):

• The -1' attempts to close an existing string literal in a SQL query.
• OR introduces an additional condition.
• 55=26 is intended as a boolean condition, but 55 equals 25, so this is false.
• -- starts a comment, so the rest of the query is ignored.

In a typical login query like: SELECT * FROM users WHERE username = '\(input' AND password = '\)password'; this payload would try to alter the WHERE clause. Whether it succeeds depends on how the input is embedded into the query:

• If the database ends up treating the injected OR as part of a valid boolean condition, it could bypass or alter the logic.
• Because 5*5=26 is false, the OR condition alone would not automatically make the whole clause true unless combined with a properly terminated string and a context that ignores the rest (which is why the -- is included). In many realistic contexts, this injection would cause a syntax error rather than a safe bypass, but the pattern demonstrates why direct string concatenation in SQL is dangerous.

Key takeaways for exams:

• This is a classic illustration of SQL injection patterns: terminate a string, inject OR with a tautology, and comment out the rest.
• The exact effect depends on how the query is constructed; it is not reliable or safe.
• The safe defense is to avoid string interpolation in SQL and use parameterized queries (prepared statements) with binding for all user inputs.
• Additional defenses: input validation, least-privilege database accounts, escaping only when truly necessary, and proper error handling (don’t reveal DB errors to users).

If you want, I can tailor a brief exam-style answer or provide a defensive checklist you can memorize for questions about SQL injection and secure coding.