Garlic essential oil, Turmeric or Eugenol can be used for this purpose.

Essential oils can be used as natural preservatives

https://www.degruyter.com/downloadpdf/j/hepo.2013.59.issue-4/hepo-2013-0030/hepo-2013-0030.pdf

Article The Potential Application of Plant Essential Oils/Extracts a...

Regards

Thanks Dear Dr. Souptik Bhattacharya for your valuable response,

Is it possible to use aqueous extract of the mentioned herbs in the formulation?

Thanks Dear H.N. Nagendra Prasad for your valuable publications. It's really helpful.

Please take a look at these useful PDF attachments.

Yes , many herbal essential oils in Iran have been already used!

Yes ancient days people used these

None of those are useful for marketed cosmetics - they're proposed causally or by academics who never marketed anything. Essential oils are not effective in this context. There a few commercial preparations (e.g. Leuconostoc ferment) but they're very weak. You asked for "completely safe" - none of these has the data supporting that claim.

Suggest this may help - https://www.youtube.com/watch?v=3s5VTSHEucs .

Phil Geis ; Thanks Prof Geis,

As you mentioned, the possibility of its usage in commercialized cosmetics is really important.

There must be some preservatives safer than parabens and their derivatives.

Thanks for the video link

Regards, Sina

Sina - please understand parabens are safe as used. This is the determination of many years of application and study and endorsed by the US FDA. The only issue of substance is sensitization and that occurs at a very low level. The "endocrine disruptor" story is technical trivia and has no relevance in real life.

The greatest risk for cosmetic preservativation is lack of efficacy. Users have been blinded and even died due to infection acquired from contaminated cosmetics.

please see https://www.fda.gov/cosmetics/cosmetic-ingredients/parabens-cosmetics

btw - there is no "totally-safe" preservative.