It depends. Slf4j is just an api, that can be using behind any of its implementions, being log4j just one. Check which one is using on the back, and if this is log4j and between versions 2.0.0 and 2.15.0 (2.15.0 is the one with the fix, versions 1.x are not affected) you should update it (if it is exposed to users directly or indirectly)

Depends on the underlying implementation of SLF4J. log4j 1.x is safe with respect to CVE-2021-44228. Thus, if your SLF4J provider/binding is slf4j-log4j12.jar, you are safe regarding CVE-2021-44228.

If you are using log4j-over-slf4j.jar in conjunction with the SLF4J API, you are safe unless the underlying implementation is log4j 2.x.

Check this - http://slf4j.org/log4shell.html

According to Apache, "only the log4j-core JAR file is impacted by this vulnerability. Applications using only the log4j-api JAR file without the log4j-core JAR file are not impacted by this vulnerability. Also Apache Log4j is the only Logging Services subproject affected by this vulnerability. Other projects like Log4net and Log4cxx are not impacted by this."

So you should be safe, as long as you do not use log4j-core package.

[,1.7.26),[1.8.0-alpha0,1.8.0-beta2) has Vulnerabilities. Please follow the link https://snyk.io/vuln/maven:org.slf4j:slf4j-ext