Small and Medium-sized Enterprises (SMEs) have become increasingly attractive targets for cybercriminals due to their growing reliance on technology and lack of resources to implement robust cybersecurity measures. This systematic literature review aims to identify the challenges and synthesize the proposals in previous studies on cybersecurity in SMEs. To identify relevant studies on this topic, the PICO model was used for the search strategy in the Scopus database, where 462 results were identified, of which 52 studies met the pre-established inclusion and exclusion criteria and were considered suitable for inclusion in the review. The findings in those studies reveal that SMEs generally lack the financial and technical resources necessary to implement robust cybersecurity measures. This situation places them in a vulnerable position against increasing cyber threats, as they tend to under-invest in cybersecurity and adopt specific solutions due to their resource constraints. This highlights the need to develop more affordable and tailored solutions to their capabilities. The studies also indicate that SMEs are particularly vulnerable to specific threats, in some cases more acute than those faced by large companies. Phishing and malware attacks were identified among the most common threats. In this context, the studies emphasized the importance of investing in continuous training programs for employees to improve the resilience of SMEs against these attacks and enhance customer trust.