If the vignetting is reasonably consistent across a batch, the practical solution is batch processing rather than manual retouching.

A few workable approaches mentioned were:

• Use a batch editor such as XnView MP and apply its Vignetting adjustment to many selected files at once.
• Use Lightroom (even a trial, if your project fits the time limit): correct one image, then sync settings to the rest and export.
• If you have help from someone technical, a simple script in Python/OpenCV or ImageMagick can automate the same kind of correction for large sets.

Important limitation: if the corners are very dark, the missing detail may not be recoverable without obvious quality loss. If the falloff is only moderate, you can brighten it, but the result may look flat or washed out unless you also fine-tune overall tone/contrast.

So yes, this is a solvable batch problem—but only when the vignette pattern is similar enough from image to image, and only to the extent that the shadowed areas still contain usable data.