Top results from Googling, "cognitive-behavioral therapy meta-analysis" (as of 21 Nov)
Stefan G. Hofmann (Jul 2012) The Efficacy of Cognitive Behavioral Therapy: A Review of Meta-analyses
We identified 269 meta-analytic studies and reviewed of those a representative sample of 106 meta-analyses examining CBT ... In general, the evidence-base of CBT is very strong.
Joseph K. Carpenter (Feb 2018) Cognitive behavioral therapy for anxiety and related disorders: A meta‐analysis of randomized placebo‐controlled trials
Looked at 41 studies where patients were randomly assigned to CBT, other psychological treatments, or a placebo.
Large effect sizes were found for OCD, GAD, and acute stress disorder, and small to moderate effect sizes were found for PTSD, SAD, and PD ... Findings demonstrate that CBT is a moderately efficacious treatment for anxiety disorders when compared to placebo.
Carpenter is a Clinical Psychology graduate student at Boston University
Andrew C. Butler (Sep 2005) The empirical status of cognitive-behavioral therapy: A review of meta-analyses
Meta-review of 16 meta-analyses, showing large effect sizes "for unipolar depression, generalized anxiety disorder, panic disorder with or without agoraphobia, social phobia, posttraumatic stress disorder, and childhood depressive and anxiety disorders.