diff --git a/routers/api/v1/repo/issue_reaction.go b/routers/api/v1/repo/issue_reaction.go
index 12be5c388f..b87d636b80 100644
--- a/routers/api/v1/repo/issue_reaction.go
+++ b/routers/api/v1/repo/issue_reaction.go
@@ -186,9 +186,19 @@ func changeIssueCommentReaction(ctx *context.APIContext, form api.EditReactionOp
 		return
 	}
 
-	err = comment.LoadIssue(ctx)
-	if err != nil {
+	if err = comment.LoadIssue(ctx); err != nil {
 		ctx.Error(http.StatusInternalServerError, "comment.LoadIssue() failed", err)
+		return
+	}
+
+	if comment.Issue.RepoID != ctx.Repo.Repository.ID {
+		ctx.NotFound()
+		return
+	}
+
+	if !ctx.Repo.CanReadIssuesOrPulls(comment.Issue.IsPull) {
+		ctx.NotFound()
+		return
 	}
 
 	if comment.Issue.IsLocked && !ctx.Repo.CanWriteIssuesOrPulls(comment.Issue.IsPull) {